Optical Coupling

ABSTRACT

Apparatuses, systems and methods for optical coupling, optical integration, electro-optical coupling, and electro-optical packaging are described herein. Optical couplers may comprise various optical elements (e.g., mirrors as described herein) to relax optical assembly requirements and improve producibility. Optical couplers may improve fiber-to-chip, fiber-to-fiber and chip-to-chip optical connection. Optical couplers and optical components may be used to improve integration of, connection of, and/or packaging of optical systems and/or components with electrical systems and/or components.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.17/989,303, filed on Oct. 17, 2022, which is a continuation-in-part ofU.S. application Ser. No. 17/674,319, filed on Feb. 17, 2022, which is areissue application of U.S. application Ser. No. 15/724,966, filed onOct. 4, 2017, which issued as U.S. Pat. No. 10,564,374, which claimspriority from U.S. Provisional Application No. 62/405,476, filed on Oct.7, 2016, U.S. application Ser. No. 15/724,966 is also acontinuation-in-part of U.S. application Ser. No. 14/878,591, filed onOct. 8, 2015, which issued as U.S. Pat. No. 9,804,334; U.S. applicationSer. No. 17/989,303 is also a continuation-in-part of U.S. applicationSer. No. 17/645,667, filed on Dec. 22, 2021; U.S. application Ser. No.17/989,303 is also a continuation-in-part of U.S. application Ser. No.17/645,673, filed on Dec. 22, 2021; U.S. application Ser. No. 17/989,303is also a continuation-in-part of U.S. application Ser. No. 17/512,200,filed on Oct. 27, 2021; U.S. application Ser. No. 17/989,303 is also acontinuation-in-part of U.S. application Ser. No. 17/120,816, filed onDec. 14, 2020, which is a continuation of U.S. application Ser. No.16/386,859, filed on Apr. 17, 2019, which issued as U.S. Pat. No.10,866,363, which claims priority from U.S. Provisional Application No.62/659,376, filed on Apr. 18, 2018, U.S. application Ser. No. 16/386,859is also a continuation-in-part of U.S. application Ser. No. 15/797,792,filed on Oct. 30, 2017, which issued as U.S. Pat. No. 10,481,334, whichis a continuation of U.S. application Ser. No. 14/878,591, filed on Oct.8, 2015, which issued as U.S. Pat. No. 9,804,334; U.S. application Ser.No. 17/989,303 is also a continuation-in-part of U.S. application Ser.No. 16/814,401, filed on Mar. 10, 2020, which claims priority from U.S.Provisional Application No. 62/795,837, filed on Jan. 23, 2019; U.S.application Ser. No. 17/989,303 is also a continuation-in-part of U.S.application Ser. No. 16/801,682, filed on Feb. 26, 2020, which claimspriority from U.S. Provisional Application No. 62/811,840, filed on Feb.28, 2019. The contents of each of the above-referenced applications areincorporated herein by reference in their entirety for all purposes.

FIELD

Aspects described herein generally relate to optical coupling,electro-optical integration, and optical and electro-optical packaging.More specifically, one or more aspects describe herein describe opticalcoupling, electro-optical integration, and optical and electro-opticalpackaging.

BACKGROUND

Modern infrastructure relies on data, and data is ever increasing.Similarly ever increasing are the demands for improved data transferspeeds and reduced energy consumption. Optics offers an alluringsolution with possible increased speed and possible decreased energyconsumption. However, challenges remain when coupling optical signals,and integrating optical components with electrical components. Thus,improved solutions to the above and other problems relating to opticsare desired.

SUMMARY

The following presents a simplified summary of various aspects describedherein. This summary is not an extensive overview, and is not intendedto identify required or critical elements or to delineate the scope ofthe claims. The following summary merely presents some concepts in asimplified form as an introductory prelude to the more detaileddescription provided below.

To overcome limitations in the prior art described above, and toovercome other limitations that will be apparent upon reading andunderstanding the present specification, aspects described herein aredirected towards improved methods, apparatuses and systems for opticalcoupling and electro-optical integration. Particularly, challengesremain with coupling optical components. For example, many opticalcoupling schemes rely on tedious side coupling, for example, highlyaccurately aligning an optical fiber with another fiber or opticalcomponent. Thus, much of the accuracy required depends on the accurateassembly.

Accordingly, aspects of the present disclosure relate to “self-aligning”optical surface coupling. The surface coupling scheme of the presentdisclosure may be achieved with a novel mirror arrangement as describedmore fully herein. Additionally, utilizing aspects of the novel mirrorarrangement, the optical components being coupled may be arranged indifferent planes. Advantages of the present disclosure are numerous anddescribed herein below in more detail. For example, some advantagesrelate to transferring the accuracy and tolerance requirements from theassembly domain to the production domain where it is significantly moreeasily achieved. Further, the accuracy and tolerance requirements in theassembly phase may be significantly reduced. Additionally, utilizingaspects of the present disclosure, numerous novel couplingconfigurations, optical packaging, and electro-optical packaging may berealized.

These and additional aspects will be appreciated with the benefit of thedisclosures discussed in further detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of aspects described herein and theadvantages thereof may be acquired by referring to the followingdescription in consideration of the accompanying drawings, in which likereference numbers indicate like features (e.g., numbers that end in thesame two digits may indicate like features) and/or like named featuresmay indicate like features, and wherein:

FIG. 1 depicts an example optical coupler according to one or moreaspects of the present disclosure.

FIG. 2 is a perspective view of an example PhotonicPlug layer comprisingreceiving features to accommodate a plurality of optical fibersaccording to one or more aspects of the present disclosure.

FIG. 3 depicts an example signal diagram according to one or moreaspects of the present disclosure.

FIGS. 4A-4C illustrate example signal diagrams having differentalignments according to one or more aspects of the present disclosure.

FIG. 5A-5C illustrate example signal diagrams having differentalignments according to one or more aspects of the present disclosure.

FIG. 6 depicts an example optical coupler according to one or moreaspects of the present disclosure.

FIG. 7A depicts an example optical coupler according to one or moreaspects of the present disclosure.

FIG. 7B shows an example optical coupler 700B according to one or moreaspects of the present disclosure.

FIG. 8 depicts an example optical coupler according to one or moreaspects of the present disclosure.

FIG. 9A, depicts a side cross-section view of an example PhotonicPluglayer according to one or more aspects of the present disclosure.

FIG. 9B depicts a front cross-section of the example fiber receivingsubstrate of FIG. 9A according to one or more aspects of the presentdisclosure.

FIG. 9C depicts a front cross-section of an example fiber receivingsubstrate according to one or more aspects of the present disclosure.

FIG. 10A depicts a cross section of an example stacked optical coupleraccording to one or more aspects of the present disclosure.

FIG. 10B depicts an example alternative stacked optical coupleraccording to one or more aspects of the present disclosure.

FIG. 10C depicts a front cross-section view of an example receivingsubstrate for a stacked optical fiber coupler according to one or moreaspects of the present disclosure.

FIG. 11 depicts an example dual-sided optical coupler according to oneor more aspects of the present disclosure.

FIG. 12A depicts an example optical coupler according to one or moreaspects of the present disclosure.

FIG. 12B depicts an example receiving substrate according to one or moreaspects of the present disclosure.

FIG. 13 depicts an example lensed optical coupler according to one ormore aspects of the present disclosure.

FIG. 14 depicts an example optical coupler according to one or moreaspects of the present disclosure.

FIG. 15 depicts an example optical coupler with a spacer adapted as aninterposer according to one or more aspects of the present disclosure.

FIG. 16A depicts an example turning curved mirror PIC I/O interface(also referred to as a photonic bump and/or a TCM photonic bump)according to one or more aspects of the present disclosure.

FIG. 16B depicts a plurality of example TCM photonic bumps on a PICsubstrate according to one or more aspects of the present disclosure.

FIGS. 16C and 16D depict example TCMs executing optical signalredirection and mode conversion according to one or more aspects of thepresent disclosure.

FIG. 16E depicts an example TCM photonic bump 1664 according to one ormore aspects of the present disclosure.

FIG. 17 depicts an example grating coupler photonic bump 1764 accordingto the present disclosure.

FIG. 18A depicts an example tapered waveguide photonic bump according toone or more aspects of the present disclosure.

FIG. 18B depicts a cross-section of the example tapered waveguidephotonic bump in a first dimension according to one or more aspects ofthe present disclosure.

FIG. 18C depicts a cross-section of the example tapered waveguidephotonic bump in a second dimension, substantially perpendicular to thefirst dimension of FIG. 18B, according to one or more aspects of thepresent disclosure.

FIG. 19 depicts an example electro-optical package according to one ormore aspects of the present disclosure.

FIG. 20A depicts an example electro-optical system according to one ormore aspects of the present disclosure.

FIG. 20B depicts an example electro-optical package according to one ormore aspects of the present disclosure.

FIG. 21 depicts an example electro-optical package according to one ormore aspects of the present disclosure.

FIG. 22 depicts an example optical coupler integrated with 2.5D and 3Delectronic packaging.

FIG. 23 depicts an example electro-optical package according to one ormore aspects of the present disclosure.

FIG. 24 depicts an example electro-optical package according to one ormore aspects of the present disclosure.

FIG. 25 depicts an example electro-optical package according to one ormore aspects of the present disclosure.

FIGS. 26A-26B depict example electro-optical packages according to oneor more aspects of the present disclosure.

FIG. 27 depicts an example configuration of multiple optical couplersconnected to a PIC according to one or more aspects of the presentdisclosure.

FIG. 28A depicts an example slotted package substrate according to oneor more aspects of the present disclosure.

FIG. 28B depicts a top view of an example electro-optical package with aslotted package substrate according to one or more aspects of thepresent disclosure.

FIG. 28C depicts a side view of the example electro-optical package witha slotted package substrate of FIG. 28B.

FIG. 29 depicts a side view of an example alternative configuration ofan electro-optical package with a slotted package substrate according toone or more aspects of the present disclosure.

FIG. 30 depicts an example electro-optical package with a partiallyslotted package substrate according to one or more aspects of thepresent disclosure.

FIG. 31 depicts an example electro-optical package with a slottedpackage substrate according to one or more aspects of the presentdisclosure.

FIG. 32 depicts an example electro-optical package with a slottedpackage substrate 3278 according to one or more aspects of the presentdisclosure.

FIG. 33A depicts an example electro-optical package with mechanicalaligners according to one or more aspects of the present disclosure.

FIG. 33B depicts an exploded view of the example electro-optical packagewith mechanical aligners of FIG. 33A according to one or more aspects ofthe present disclosure.

FIG. 34A depicts an example chip-to-chip optical connectivity schemeaccording to one or more aspects of the present disclosure.

FIG. 34B depicts an example chip-to-chip optical connectivity schemeaccording to one or more aspects of the present disclosure.

FIG. 35 depicts a plurality of example TCM photonic bumps and opticalwaveguides according one or more aspects of the present disclosure.

FIG. 36A depicts an example electro-optical package according to one ormore aspects of the present disclosure.

FIG. 36B depicts an example electro-optical package according to one ormore aspects of the present disclosure.

FIG. 37 shows an example method for making a structure and coupling ofsingle-mode fiber to a silicon photonics chip that is flip-chip mountedusing backside optical coupling according to one or more aspects of thepresent disclosure.

FIG. 38 shows an example cavity as having been formed in top of SiPhchip 3801.

FIG. 39 depicts example antireflective coating layers applied along thebottom of cavity and along a portion of bottom of SiPh chip according toone or more aspects of the present disclosure.

FIG. 40 shows an example imprint material in cavity and also someexample imprint material on top of SiPh chip along with example imprintstamp according to one or more aspects of the present disclosure.

FIG. 41 shows an example shaped and hardened imprint material withcurved surface and tilted flat surface following cleaning of anypossible non-hardened imprint material according to one or more aspectsof the present disclosure.

FIG. 42 depicts example reflective material deposited on the exampleimprint material according to one or more aspects of the presentdisclosure.

FIG. 43 depicts the example of FIG. 42 with example electrical bumps onthe SiPh chip according to one or more aspects of the presentdisclosure.

FIG. 44 shows example SiPh chip flipped and mounted to an examplesubstrate after reflow of solder microbumps.

FIG. 45 depicts an example photonic plug coupled to a SiPh chipaccording to one or more aspects of the present disclosure.

FIG. 46 depicts a portion of an example surface usable for a photonicplug according to one or more aspects of the present disclosure.

FIG. 47 shows an example of a fully assembled detachable connector forco-packaged optics coupled to a multi-chip module via a PIC according toone or more aspects of the present disclosure.

FIG. 48 shows an exploded view of the example that is shown in FIG. 47 .

FIG. 49 shows another view of example detachable plug die inserted intoexample receptacle according to one or more aspects of the presentdisclosure.

FIG. 50 shows an exploded view of the example of FIG. 49 but withoutoptical fibers according to one or more aspects of the presentdisclosure.

FIG. 51 shows example individual fibers of a fiber ribbon inserted intoexample trenches of a photonic plug die according to one or more aspectsof the present disclosure.

FIG. 52 shows a cross sectional view of an example detachable connectorif assembled and an example optical path according to one or moreaspects of the present disclosure.

FIG. 53 is a top view of an example electro-optical interconnectionplatform 5300 according to the present disclosure.

FIG. 54 is an example magnified view of the example electro-opticalinterconnection platform according to present disclosure.

FIG. 55 is an example schematic side view of the example electro-opticalinterconnection platform according to the present disclosure.

FIG. 56 is an example diagram of a high magnification of the examplefiberless optical coupler according to one or more aspects of thepresent disclosure.

FIG. 57 is a schematic side view of an example fiberless optical coupleron the PIC according to the present disclosure.

FIG. 58 is a schematic side view of the example fiberless opticalcoupler on the PIC that is attached to the fiber array, according to oneor more aspects of the present disclosure.

FIG. 59 is a schematic side view of an example electro-opticalinterconnection platform according to one or more aspects of the presentdisclosure.

FIG. 60 is an example method of manufacturing an electro-opticalinterconnection platform, according to one or more aspects of thepresent disclosure.

FIG. 61 is a schematic side view of an example electro-opticalinterconnection platform according to the present disclosure.

FIG. 62 shows an example co-packaged optics with a plurality of lasermodules according to one or more aspects of the present disclosure.

FIG. 63 depicts an example laser module according to one or more aspectsof the present disclosure.

FIG. 64 show an example laser coupled to a fiber utilizing one or moreaspects of an example optical coupler of the present disclosure.

DETAILED DESCRIPTION

The accompanying drawings, which form a part hereof, show examples ofthe disclosure. It is to be understood that the examples shown in thedrawings and/or discussed herein are non-exclusive and that there areother examples of how the disclosure may be practiced. It is to beunderstood that structural and functional modifications may be madewithout departing from the scope described herein.

It is to be understood that the phraseology and terminology used hereinare for the purpose of description and should not be regarded aslimiting. Rather, the phrases and terms used herein are to be giventheir broadest interpretation and meaning. The use of “including” and“comprising” and variations thereof is meant to encompass the itemslisted thereafter and equivalents thereof as well as additional itemsand equivalents thereof. The use of the terms “mounted,” “connected,”“coupled,” “positioned,” “engaged” and similar terms, is meant toinclude both direct and indirect mounting, connecting, coupling,positioning and engaging.

According to aspects of the present disclosure, the optical couplersdisclosed herein may be used and configured to optically connect two ormore optical components. Additionally, the optical couplers of thepresent disclosure may facilitate electrical connection of electricalcomponents, photonic components, and/or optoelectrical components.Optical components may comprise, for example, optical only components,optical-electrical components, photonic components, etc. Opticalcouplers may couple a light beam, referred to herein as beam, lightbeam, signal, an optical signal, signal beam, etc., between a sourceoptical component and a drain optical component (e.g., destination, ortarget, etc.). As will be appreciated from the present disclosure,optical signals may propagate through the coupler in multipledirections. As such a source optical component in one application may bethe drain optical component in a subsequent application. Thus, unlessexpressly stated otherwise, it is to be assumed that every opticalconnection described in the present disclosure may operate in thereverse from that which is expressly stated. Similarly, unless expresslystated otherwise, a component described as an “optical source component”may be the “optical drain component” in a reversed connection direction,and vice versa. Thus, unless expressly stated otherwise herein, opticalsource components and optical drain components may be referred to asoptical source/drain components.

Examples of optical components, which may act as and/or be configuredsimilarly to source/drain optical components, may comprise, but are notlimited to, optical waveguides, optical fibers (e.g., any type ofoptical fiber), grating couplers, photonic integrated circuits (PICs),lasers, mirrors, amplifiers, multiplexers, demultiplexers, splitters,mode adapters, etc. For example, according to aspects of the presentdisclosure, an optical coupler may be configured and implemented tooptically connect one or more optical fibers (e.g., optical components)to a photonic integrated circuit (PIC) (e.g., integrated optical circuitoptical component). The PIC may be optically and/or electrically coupledto further components (e.g., electrical circuits, optical circuits,etc.) as will be described in more detail herein. According to aspectswhere an optical coupler couples a PIC to an optical fiber, both the PICand the optical fiber may be the source optical component or the drainoptical component.

Many advantages of the present disclosure may be appreciated. Forexample, aspects of the present disclosure may take advantage of opticalelements (e.g., turning mirrors, curved mirrors, etc.) to performoptical signal manipulation and facilitate optical connection of opticalcomponents. Aspects of the present disclosure may enable high volumepackaging of photonic devices. Additionally, aspects of the presentdisclosure may allow for simplified assembly optical connection of alarge number of optical components (e.g., optical fibers and PICs).Utilizing aspects of the present disclosure, the efficient integrationof optical and electrical components may additionally be realized.

Further still, aspects of the present disclosure may take advantage ofthe optical scheme herein to enable large assembly tolerances whenconnecting optical components. The optical scheme may take advantage ofwafer level processes for accurate placement of optical elements onseparate planes. Such processes may relax the assembly tolerance foroptical systems. Further still, aspects of the present disclosure allowfor optical surface coupling and/or optical interconnection ofcomponents that are out of plane with one another, further realizingrelaxed assembly tolerances and enabling great configurability. Furtherstill, some aspects of the present disclosure may be fabricated atvolume that may leverage existing ecosystems and workflows, for example,using complementary metal-oxide-semiconductor (CMOS) processes,silicon-on-insulator (SOI) processes, nanoimprint lithography (NIL),grayscale lithography, hot embossing, photoresist additivemanufacturing, etc. In addition to front-end processes, aspects of thepresent disclosure may benefit from improved back-end processes (e.g.,improved wafer level testing). The above advantages, and more, may beappreciated and further discussed in context hereinbelow.

FIG. 1 depicts an example optical coupler 100 according to one or moreaspects of the present disclosure. Referring to FIG. 1 , optical coupler100 may optically couple an optical fiber 102 (e.g., opticalsource/drain component) and a PIC 104 (e.g., optical source/draincomponent) (PIC as described herein may be understood as a standalonephotonic integrated circuit or as a chiplet, and may comprise an opticalengine, an optical engine and a PIC, and/or an optical engine and/or aPIC packaged with additional components (e.g., package substrates,electrical components, optical components, etc.)). Such an arrangementmay be considered a fiber-to-chip optical connection. As will beappreciated by persons of ordinary skill, optical coupler 100 may beconfigured to optically couple various optical components, for example,fiber-to-fiber, and chip-to-chip, and other connections that will beunderstood from the present disclosure.

Referring to FIG. 1 , as an overview, the optical coupler 100 maycomprise Photonic Plug layer 106, spacer layer 108, PIC layer 114, andone or more mirrors that may comprise one or more of first curved mirror110, second curved mirror 112, first turning mirror 120. According toaspects, optical coupler 100 may comprise one or more additionalcomponents and/or layers, and one or more depicted components and/orlayers may be omitted from optical coupler 100. The description of“layers” in the preset disclosure is meant for purposes of illustrationonly in order to more readily understand aspects and benefits of thepresent disclosure. It should be understood that an optical couplerdescribed herein, or optical interconnection scheme described herein,may comprise one or more additional “layers.” Additionally, one or moreof the described “layers” may be omitted. For example, the opticalcoupler may only comprise PhotonicPlug layer 106 and spacer layer 108.Further still, any illustrated “layer” may comprise any number ofsubstrates as will be understood from the present disclosure.“PhotonicPlug” may be referred to herein as a Photonic Plug, PP,photonic plug, or similar.

Referring to FIG. 1 , optical signal 116 may enter and exit the opticalcoupler 100 via optical fiber 102 (e.g., optical source/draincomponent). Optical fiber 102 may be coupled with the PhotonicPlug layer106. As will become clear from the present disclosure, optical fiber 102may be coupled to PhotonicPlug layer 106. Accordingly, optical signal116 may propagate through the optical coupler 100 between the opticalfiber 102 and the PIC 104. Optical signal 116 may propagate through theoptical coupler 100 from the optical source (e.g., optical fiber 102) tothe optical drain (e.g., PIC 104), via the series of mirrors (e.g.,reflectors). One or more mirrors may be comprised in the PhotonicPluglayer 106. Referring to FIG. 1 second curved mirror 112 may befabricated on, added to, manufactured in, or otherwise integrated withPhotonicPlug layer 106. Optical fiber 102, and other optical components,may be variously coupled to, and retained in or on PhotonicPlug layer106. According to further aspects, optical source/drain components(e.g., optical fiber 102) may not be attached to the optical coupler atPhotonicPlug layer 106 but at a different layer or component (e.g.,attached to spacer 118, PIC layer 114). Additional details and aspectsof the PhotonicPlug layer 106 will be described herein below.

Optical coupler 100 may comprise spacer layer 108 between first curvedmirror 110 and second curved mirror 112. Spacer layer 108 may operateand/or be configured to suitably space the first curved mirror 110 fromthe second curved mirror 112 according to design considerations (e.g.,desired vertical distance between first curved mirror 110 and secondcurved mirror 112). Spacer layer 108 may comprise one or moresubstrates. Spacer layer 108 may comprise, for example, one or more ofthe substrate spacer 118. Spacer 118 may comprise and/or be comprised ofa material that is substantially transparent to the wavelength of theoptical signal, and may be substantially non-conductive such thatoptical signals may propagate through spacer 118 with sufficient lack ofattenuation. Spacer 118 may be fabricated from, for example, glass,polydimethylsiloxane, epoxy, resin, silicon, or any material with asuitable index of refraction as would be understood by persons ofordinary skill in the art. According to other aspects, spacer layer 108may be an empty space (e.g., an air gap between first curved mirror 110and second curved mirror 112). According to such aspects, additionalfeatures may be used to appropriately space first curved mirror 110 fromsecond curved mirror 112 (as described in more detail herein). Accordingto yet further aspects, spacer layer 108 may comprise spacer 118 inconjunction with an air gap as will be understood from the presentdisclosure. Spacer layer 108 may additionally comprise an interposerspacer that may further act as and/or be configured similarly to apassive electrical component to facilitate various electrical andoptical connections between various circuits and components as will bedescribed in more detail herein. While spacer 118 is depicted in FIG. 1as being formed of one substrate, spacer layer 108 may comprise anynumber of substrates. The spacer layer 108 and/or spacer substrate 118may act as and/or be configured as an encapsulant which may assist inprotecting optical elements and/or components herein (e.g., first curvedmirror 110, second curve mirror 112, first turning mirror 120, and/oroptical fiber 102). Additional details and aspects of the spacer 118and/or spacer layer 108 are described hereinbelow.

Optical coupler 100 may couple an optical signal 116 between an opticalsource component and an optical drain component. Such components maycomprise, for example, optical fiber 102 (e.g., optical source/draincomponent) and PIC 104 (e.g., optical source/drain component). The PIC104 may be comprised in PIC layer 114. PIC layer 114 may comprise asingle substrate or any number of substrates as will be describedherein. For example, PIC layer 114 may comprise PIC substrate 122. PICsubstrate 122 may be fabricated from and/or comprise, for example, asilicon photonic (SiPh) chip. Additionally or alternatively, PICsubstrate 122 may be fabricated from and/or comprise, for example,silicon, silica, lithium niobite, indium phosphide (InP), siliconnitride (Si₃N₄), or any other material suitable to fabricate photoniccircuits. PIC 104 may be fabricated in PIC substrate 122. Alternatively,PIC 104 may be added as an additional component to PIC substrate 122and/or one or more additional substrates of PIC layer 114. According toaspects, as will be understood herein, PIC layer 114 may comprise anynumber of substrates. PIC 104 may comprise PIC I/O interface 128(described in more detail herein) interface and, optionally manipulate,received and/or transmitted optical signals with PIC 104. AccordinglyPIC 104 (via, for example, PIC I/O interface 128) may act as and/or beconfigured similarly to an optical source and/or an optical draincomponent.

PIC layer 114 may comprise one or more additional components orelements. Accordingly, first curved mirror 110 may be fabricated on,added to, manufactured in, or otherwise integrated with PIC 104. Firstcurved mirror 110 may be integrated with PIC layer 114 in numerousdifferent manners as described in more detail herein. According toaspects, PIC layer 114 may be viewed as a component that is separatefrom the optical coupler, and to which an optical coupler may becoupled. According to such aspects, optical coupler (comprising, e.g.,PhotonicPlug layer 106 and spacer layer 108) may be added to an existingPIC 104 and/or PIC layer 114 to facilitate optical connection between anoptical component attached to the optical coupler (e.g., an opticalfiber at the PhotonicPlug layer) and the separate PIC layer 114.According to such aspects and other aspects described herein, opticalelements (e.g., first curved mirror 110) may be added to an existing PIClayer 114 to facilitate optical connection to/from the PIC 104 (in PIClayer 114) according to the schemes of the present disclosure.Alternatively, PIC layer 114 may be understood as a part of the opticalcoupler 100. Additional details and aspects of the PIC layer 114 and PIC104 are described herein.

As briefly described, referring to FIG. 1 , optical coupler 100 may useone or more mirrors to couple optical signals 116 between an opticalsource component and an optical drain component. Accordingly, opticalcoupler 100 may comprise first curved mirror 110 and second curvedmirror 112. According to aspects, curved mirrors 110 and 112 may beconsidered, for example concave mirrors. The curved mirrors 110 and 112,arranged according to the present disclosure, may facilitate theadvantageous optical interconnection schemes described herein. Curvedmirrors (e.g., first curved mirror 110 and second curved mirror 112) mayprovide multiple functions. The curved mirrors 110 and 112 maymanipulate (e.g., collimate, parallelize, redirect, and/or focus)optical signal 116. The curved mirrors 110 and 112 may additionallyreflect direct, and/or redirect the manipulated optical signal 116through the optical coupler 100. For example, referring to FIG. 1 ,assuming the optical signal 116 propagates in the direction from firstcurved mirror 110 to second curved mirror 112, optical signal 116 may beincident on first curved mirror 110 where first curved mirror 110 mayreceive optical signal from the optical source. The first curved mirror110 may receive the optical signal 116, substantially collimate (e.g.,substantially parallelize) the optical signal, and reflect thesubstantially collimated optical signal in the direction of the secondcurved mirror 112. Alternatively, in some configurations the firstcurved mirror 110 may not collimate the optical signal 116. In suchconfigurations, the first curved mirror 110 may otherwise manipulate theoptical signal 116 (e.g., redirect the optical signal). The secondcurved mirror 112 may receive the optical signal 116, may substantiallyfocus the optical signal 116, and reflect the substantially focusingoptical signal toward the optical drain.

As will be appreciated from the present disclosure, additional mirrorsmay be used in an optical coupler to facilitate the opticalinterconnection between source and drain. Referring to FIG. 1 , opticalcoupler may further comprise first turning mirror 120. First turningmirror 120 may interface the optical signal 116 with the remainder ofthe optical coupler 100. For example, first turning mirror 120 mayrelay, or receive and reflect the optical signal 116 from the opticalfiber 102 toward the first curved mirror 110. Thus, as is described inmore detail herein, the first turning mirror 120 may allow for variousplacement and alignment of the optical fiber 102 (e.g., parallel toPhotonicPlug layer surface) with respect to the rest of the opticalcoupler 100 and optical components. First turning mirror 120 may beconfigured as a substantially flat mirror. First turning mirror 120 maybe variously angled with respects to the optical source (e.g., opticalfiber 102) to turn, direct, and/or re-direct optical signal 116.According to additional aspects, the first turning mirror 120 may alsobe a curved mirror, to variously manipulate optical signals in anoptical coupler (e.g., to achieve optical signal mode size conversion).Additional details and aspects of the first turning mirror 120 aredescribed herein.

Some of optical interconnection schemes of the present disclosure areillustrated and described with respect to mirrors only. However, it willbe understood by persons of ordinary skill in the art, that the opticalinterconnection schemes herein may be practiced with alternative opticalelements. For example, instead of one or more of the curved mirrors, thepresent scheme may be practiced with a combination of lenses andmirrors. For example, in place of first curved mirror 110 and/or secondcurved mirror 112, lenses may be paired with flat mirrors to achieve asimilar interconnection scheme (as described in more detail herein).Additionally, the term “mirror” is used to describe a reflective surfacethat may reflect at least some wavelengths of light. The term “mirror”may be understood to comprise reflector, reflective surface, diffractivelensing mirror, etc., or the like.

It should be understood that, although a some of the FIGS. areillustrated in two dimensions (e.g., a two dimensional-cross section),and therefore only depict a cross-section of single optical fiber,aspects of the present disclosure may be practiced with numerous opticalfibers per single optical coupler. FIG. 2 is a perspective view of anexample PhotonicPlug substrate 226 comprising receiving features224A-224D (generally receiving feature 224) to accommodate a pluralityof optical fibers 202 (e.g., optical fiber 202A and optical fiber 202B)according to one or more aspects of the present disclosure. Referring toFIG. 2 , PhotonicPlug substrate 226 may comprise a plurality ofreceiving features 224 for a plurality of optical fibers 202 (e.g., toreceive an optical fiber ribbon). Similarly, PhotonicPlug substrate 226may comprise a plurality of first turning mirrors 220A-220D (generallyfirst turning mirror 220), one for each, or some, of the optical fiberconnections. Similarly, the PhotonicPlug substrate 226 may comprise aplurality of second curved mirrors 212A-212D (generally second curvedmirror 212) for each, or some, of optical fiber connections. While FIG.2 depicts the receiving features 224, the first turning mirrors 220, andsecond curved mirrors 212 as being integrated within a single substrate(e.g., PhotonicPlug substrate 226), these features may be incorporatedin any combination of different substrates. While FIG. 2 , shows anexample of a portion of an optical coupler comprising four receivingfeatures 224, optical couplers are contemplated herein to comprise anynumber of receiving features (and additional elements, e.g., firstturning mirror, second curved mirror, etc.) to connect any number ofoptical fibers. Additionally, only two fibers are depicted for ease ofillustration, however any number of fibers are contemplated.

Aspects of the present disclosure relate to the curved mirrors and howthey may be leveraged to optically connect components. FIG. 3 depicts anexample signal diagram according to one or more aspects of the presentdisclosure. The signal diagram may be understood as depicting an examplepath of a light beam or optical signal 316 in an optical coupler (e.g.,optical coupler 100) as well as depicting example optical manipulationassociated with optical elements and aspects of the presentinterconnection scheme. Referring to FIG. 3 , first curved mirror 310and second curved mirror 312 may be oriented in substantially opposingdirections. Thus, the reflective surfaces (or the vertex of the curvedmirrors 310 and 312) may be facing substantially opposing directions.According to aspects, as will be described herein, one or more of thecurved mirrors 310 and/or 312 may be oriented variously (e.g., notsubstantially opposed, see for example FIG. 7B). According to designconsiderations, first and second curved mirrors 310 and 312 may bevariously oriented in relation to one another. First and second curvedmirrors 310 and 312 may be facially spaced from one another by distanceL. Facial spacing may be considered the space or distance between thevertexes of the first and second curved mirrors 310 and 312. While thisspacing is illustrated as a vertical spacing in FIG. 3 , according toaspects wherein the optical coupler is oriented differently, facialspacing may be achieved in any direction (e.g., facial spacing may be inthe horizontal direction where the orientation of the coupler is rotated90° from the example orientation in FIG. 3 ). Additionally, first andsecond curved mirrors 310 and 312 may be laterally distanced from oneanother. Lateral spacing may be considered the lateral distance betweenthe vertices of the first and second curved mirrors 310 and 312. Inaddition to the relative spacing between curved mirrors, designconsiderations may comprise the distance between the curved mirrors andsource, and the curved mirrors and drain (e.g., D1 and D2 in FIG. 3 ).

Some design parameters may be further understood with reference to theexample signal diagram in FIG. 3 . The optical signal 316 may beunderstood as propagating through an optical coupler at main propagationangles: first propagation angle, α; second propagation angle, β; andthird propagation angle, γ. Assuming, for purposes of illustration thatoptical source/drain component 302 (e.g., optical fiber, PIC I/Ointerface, laser, photonic bump, etc.) is a point (a point is anidealized case for ease of description and understanding, the opticalsource/drain component 302 may not be a point but may have dimension(e.g., the optical source/rain component may have a beam waist, forexample, in the range of 1-10 μm)). First propagation angle, α, may bedefined as the angle of propagation of the optical signal 316 from aplane that intersects the optical source/drain component 302 in avertical direction to the center axis of the optical signal 316propagating from (or to) the optical source/drain component 302. Theoptical signal 316 may diverge as it propagates from opticalsource/drain component 302 (or converge toward optical source drain302). The angle of divergence, θ, may be defined as the angle from thecenter axis of the optical signal 316 to where the intensity of theoptical signal 316 is 1% of the intensity at the center of the opticalsignal 316 (angle of divergence may be defined to different intensitiesdepending on design considerations). Second propagation angle β, may be,for example, the angle between the center axis of the optical signal 316approaching first curved mirror 310, and the center of the opticalsignal 316 receding from first curved mirror 310. Third propagationangle, γ, may be, for example, the angle between the center axis of theoptical signal 316 approaching second curved mirror 312 and the centerof the optical signal 316 receding from second curved mirror 312.

According to examples, the propagation angles may be designed where:

α+β>0; and

2α=β=γ

The value of α may range from 0°, or just above 0°, to about 45° or even60°. Potentially some situations may call for a narrower range, forexample, 8° to 12° which in some circumstance can provide improvedefficiency. According to some configurations, the angle of a may beselected to reduce back reflections (for example, to the optical sourceand/or drain components). According to aspects, different designconstraints may be used depending on design considerations.

According to aspects, the first and second mirrors 310 and 312 may beconfigured and arranged such that the center axis of the optical signal316 intersects each mirror 310 and 312 substantially near the vertex ofeach of the mirrors. For example, the mirrors may be arranged such thatthe vertex of the second curved mirror 312 may be disposed at a lateraldistance D1 from the optical source component 302. According to exampleaspects, the distance D1 may be calculated as follows:

$D_{1} = {{L*\tan(\alpha)} + {L*\tan{\left( \frac{\beta}{2} \right).}}}$

Additionally, according to example aspects, the vertex of the firstcurved mirror 310 may be disposed at a distance D2 from the opticaldrain component 328 (e.g., optical fiber, PIC I/O interface, laser,photonic bump). According to example aspects, the distance D2 may becalculated as follows:

$D_{2} = {{L*\tan\left( \frac{\gamma}{2} \right)} + {L*\tan{\left( \frac{\beta}{2} \right).}}}$

Further, the lateral distance D3 between the vertex of the first mirror310 and the vertex of the second mirror 312 may be computed as:

D ₃ =L*tan(β).

The above example design calculations may be considered according toaspects having zero misalignment.

Each curved mirror may have a radius of curvature and an associatedfocal length. Referring to FIG. 3 , the first curved mirror 310 may havea first radius of curvature RC1 and the second curved mirror 312 mayhave a second radius of curvature RC2. It should be understood from theabove that the design and/or configuration of the optical coupler may beadjusted by adjusting one or more parameters, for example, one or moreof distances, L, D1, D2, and/or D3, and/or radius of curvatures RC1and/or RC2. Thus, it should be appreciated that many configurations ofthe optical coupler may be achieved by varying the above parameters.

The above described angles and calculations describe a specificconfiguration and use. Different configurations are described herein(e.g., a spacer with an air gap, a silicon spacer, an air gap an nophysical spacer, different spacer heights, etc.). Differentconfigurations, for example, having a spacer with a different index ofrefraction, may comprise different distances D1 and D2, and D3,different angles: θ, α, β, and γ, and different radii of curvature RC1and RC2, and may be defined by different equations.

In view of the above, and considering FIGS. 4A-5C, some advantages ofthe present disclosure may be understood. FIGS. 4A-4C depict examplesignal diagrams having different alignments according to one or moreaspects of the present disclosure. In optical coupling, high accuracy isdesired between the two optical components being coupled. According tothe present disclosure, the accuracy desired for connecting opticalcomponents may be transferred from the assembly domain to thefabrication domain (where high accuracy is more easily achieved).Accordingly, the accuracy required for optical assembly may be moreeasily achieved as the accuracy may be achieved by wafer level processesand other manufacturing techniques as opposed to assembly processes.These large assembly tolerances (e.g., 10's of microns per 1 dB ofinsertion loss in X, Y, and Z axes) solve a major packaging problem inphotonic integrates circuits, e.g., fiber to chip, laser to chip, and/orchip to chip connectivity.

FIGS. 4A-4C each depict an optical component 402 (e.g., an opticalfiber) a turning mirror 420, a first curved mirror 410, a second curvedmirror 412, a PIC I/O interface 428, and an optical beam 416 (e.g.,optical signal). As it can be seen from FIGS. 4A-4C, the turning mirror420 and the second curved mirror 412 may be spaced a distance from eachother. The distance may be set to achieve the optical coupling schemeaccording to the present disclosure. This distance may be accuratelyachieved during fabrication of the turning mirror 420 and/or the secondcurved mirror 412. Similarly, the first curved mirror 410 and the PICI/O interface 428 may be distanced from each other. This distance may besimilarly accurately achieved during fabrication of the first curvedmirror 410 and/or the PIC I/O interface. In addition, utilizing aspectsof the present disclosure, it may be appreciated that different elementsmay be located on different planes. For example, the first turningmirror 420 may be located in a first plane, and the corresponding PIC(e.g., to which optical component 402 may be optically coupled) may belocated in a second plane that is different from the first plane.Additionally, the second curved mirror 412 and/or the optical component402 may be located in the first plane, and the first curved mirror 410and/or the PIC I/O interface 428 may be located in the second plane.Accordingly, elements may be located in two (or more) planes.Additionally, elements may, for purposes of depiction, be considered inan upper plane (e.g., elements in PhotonicPlug layer 106 of FIG. 1 ) anda lower plane (e.g., elements in PIC layer 114 of FIG. 1 ). With therelative distance of the optical elements accurately achieved duringfabrication, assembly tolerances of the two planes (e.g., PhotonicPlugsubstrate 126 with PIC 104) may be relaxed. For instance, FIGS. 4A-4Cdepict various optical element and optical component assembly alignments(e.g., some misaligned) and the effects the alignment may have (or nothave) on the optical connection.

As will be understood from the present disclosure, in order to assemblethe optical coupler to effect an optical connection, the elements in anupper plane (e.g., the optical component 420, the first turning mirror420 and the second curved mirror 412) (e.g., where the elements in theupper plane are installed to and/or fabricated in a PhotonicPlug layerand/or a spacer layer) are installed to and/or with elements in a lowerplane (e.g., first curved mirror 410, PIC I/O interface) (e.g., wherethe elements in the lower plane are installed to and/or fabricated in aPIC layer). FIG. 4A depicts an example installation where the upperplane and lower plane are illustrated as perfectly aligned (e.g., zeromisalignment). Accordingly, it can be seen that the optical beam 416 maypropagates from the turning mirror 420 and may be incident upon thefirst curved mirror 410. The first curved mirror 410 may substantiallycollimate the beam 416 and reflect the beam 416 toward the second curvedmirror 412. The substantially collimated beam 416 may be incident uponthe second curved mirror 412. The second curved mirror 412 maysubstantially focus the beam 416 and reflect the beam 416 toward the PICI/O interface 428. FIG. 4B depicts an example installation where theupper plane and lower plane are illustrated as positively misaligned inthe X direction. However, due to the novel scheme of the presentdisclosure, the optical beam may still propagate as described withrespect to FIG. 4A, and the optical component 402 may still be connectedto the PIC I/O interface without significant attenuation. Thus, it canbe appreciated that the accurate placement, during fabrication, of theturning mirror 420 with respect to the second curved mirror 412, and ofthe first curved mirror 410 with respect to the PIC I/O interface 428,allows for relaxed assembly tolerance requirements and may allow forimproved reliability of the optical connection, even with some assemblymisalignment. Similarly, FIG. 4C depicts an example installation wherethe upper plane and lower plane are illustrated as negatively misalignedin the X direction. Like the zero-misalignment case and the positivemisalignment case, it can be seen from FIG. 4C that an effective opticalconnection may be achieved using the present disclosure even with somenegative misalignment. Accordingly, it will be appreciated that byshifting the accuracy requirement to the fabrication domain (wherehigher accuracy is more easily achieved), accuracy requirements and/ortolerance requirements for assembly may be relaxed and overall accuracymay be more easily achieved.

While FIGS. 4A-4C, have been discussed for purposes of illustration asmisalignment in the X direction, it should be understood that the samefigures (FIGS. 4A-4C) also depict the principles of the presentdisclosure in the Y direction. Thus, it should be understood thatutilizing the present disclosure, assembly misalignment in the Ydirection may be similarly relaxed based on the same principals.

FIG. 5A-5C illustrate example signal diagrams having differentalignments according to one or more aspects of the present disclosure.Referring to FIGS. 5A-5C, it may be understood that misalignment in theZ direction may similarly be mitigated utilizing the principals of thepresent disclosure. FIG. 5A depicts a perfectly aligned (zeroZ-misalignment) case. FIGS. 5B and 5C illustrate a positiveZ-misalignment (planes spaced further) and negative Z-misalignment(planes spaced closer) respectively. As can be seen from FIGS. 5A and5B, similar to the principles discussed above with respect to FIGS.4A-4C, the schemes of the present disclosure may mitigate some of theeffects of Z assembly misalignment. Referring to FIG. 5B it can be seenthat where the two planes (e.g., the plane with the turning mirror 520and second curved mirror 512 and the plane with the first curved mirror510 and the optical drain 528) are positively misaligned in the Zdirection, the signal diagram is still achieved, and the optical source502 may be efficiently coupled to the optical drain 528. Additionally,referring to FIG. 5C, it can be seen that where the two planes arenegatively misaligned in the Z direction, the signal diagram is stillachieved and the optical source 502 may be efficiently coupled to theoptical drain. Accordingly, at least in view of FIGS. 4A-5C it may beappreciated that the tolerance requirements classically required in theassembly domain may be shifted to the fabrication domain where suchtolerances are more easily achieved (e.g., by production machines) involume. Subsequently, assembly tolerances in the X, Y, and Z directionsmay be relaxed. Similarly, tilt and rotation misalignment may be morecontrolled via the fabrication domain (e.g., wafer level mechanicalstructures) using the couplers of the present disclosure.

Some details of the “self-aligning” optics of the present disclosurehave been described with respect to FIGS. 3-5C. Referring to FIGS. 3-5C,following is a description of example equations that may define anexample tolerance map relating to the present disclosure:

d = d(h, α) < 4 * h * tan (α); Ω = f(h, n, Ω₀, α) > Ω₀,  ∝ h;${{{T\left( {x,y} \right)} \propto {{Convolution}\left( {{{Circ}\left( {\frac{x}{\left( \frac{d}{2} \right)},\ \frac{y}{\left( \frac{d}{2} \right)}} \right)},{field}} \right)}} = {{{Circ}\left( {\frac{x}{\left( \frac{d}{2} \right)},\ \frac{y}{\left( \frac{d}{2} \right)}} \right)}*\Omega}};$

Where T may be understood as the tolerance width, Ω, may be understoodas the beam spot distribution on the curved mirror (e.g., first curvedmirror 310 and second curved mirror 312), Ω₀ may be understood as thedistribution of the field on an element of the PIC I/O interface (e.g.,distribution of the field on the TCM 1660, the grating coupler 1755 orthe photonic bump turning mirror 1850, etc.), d may be understood as theaperture, n, may be understood as the index of refraction of thepropagation medium, h may be understood as the height of the spacer(e.g., L in FIG. 3 ), and a may be understood as the angle of incidence.

Referring to FIG. 1 , according to aspects herein, first curved mirror110 may be fabricated on, added to, manufactured in, or otherwiseintegrated with, PIC layer 114. For example, PIC layer 114 may compriseat least one PIC substrate 122 of a semiconductor material, for example,indium phosphide, silicon oxide (SiO₂), silica, or the like. Accordingto aspects, such a PIC substrate 122 may be arranged adjacent to spacerlayer 108. Accordingly, first curved mirror 110 may be fabricated on thesurface of PIC substrate 122 which may be adjacent to spacer layer 108.The first curved mirror 110 may be fabricated on the surface of such asubstrate in different ways. For example, first curved mirror 110 may befabricated using, for example, nanoimprint lithography (NIL),Silicon-On-Insulator (SOI) processes, complementary metal-oxidesemiconductor (CMOS) processes, grayscale lithography, and similar,and/or other process as described herein. Additional processes areconsidered herein, for example, the first curved mirror 110 may be addedto the PIC as a separate mirror substrate (e.g., a carrier placedaccurately on the PIC substrate 122). For example, a glass substrate maycomprise a curved mirror (e.g., the first curved mirror 110). The glasssubstrate be accurately placed on and attached to the PIC substrate 122.The glass substrate and/or the PIC substrate 122 may have alignmentmarks to assist in accurate placement of the glass substrate on the PICsubstrate 122. Thus, it may be appreciated that one possible advantageof the present disclosure is the ability to fabricate aspects herein, involume, using existing eco-systems and fabrication processes.Additionally, novel eco-systems and fabrication process for some opticalelements are also described herein. Any fabrication method and/orprocess may be used in which accurate placement of the components may beachieved. According to aspects, first curved mirror 110 may be coatedwith a dielectric layer to improve reflectivity (e.g., for specificoptical signal wavelengths). Such layers may comprise, but are notlimited to, a metal (e.g., aluminum, chromium, gold, silver, etc.)layer. Additionally, it may be appreciated that an advantage of thepresent disclosure is to shift the tolerance requirements for opticalconnection from the assembly phase to the production phase where higheraccuracy is more simply achieved. While some aspects of the presentdisclosure may be produced using existing methods, some aspects of thepresent disclosure relate to novel methods of production (for exampleone or more aspects described in relation to backside coupling withreference to FIGS. 37-45 ) as will be described in more detail.

According to aspects, the PIC layer substrate (e.g., upon which firstcurved mirror 110 may be fabricated), may or may not be the samesubstrate in which PIC 104 is comprised. Therefore, it is contemplatedthat according to aspects where PIC 104 and first curved mirror 110 areincluded in the same substrate, the first curved mirror 110 may befabricated at the same time, and using the same facilities in which, PIC104 is fabricated. Alternatively, even though PIC 104 and first curvedmirror 110 may be included in the same substrate, PIC 104 and firstcurved mirror may be fabricated at different times in the same facilityor different facilities. It is contemplated that first curved mirror 110and PIC 104 may be comprised in separate substrates of PIC layer 114.Referring to FIG. 1 , PIC 104 may be comprised in first PIC layersubstrate 122. First curved mirror 104 may be comprised in second PIClayer substrate 122. According to such aspects, second PIC layersubstrate 122 may be fabricated from a semiconductor material or maycomprise a layer of semiconductor material. First curved mirror 110 maybe formed on the semiconductor layer of second PIC layer substrate 122using substantially the same fabrication methods (e.g., CMOS, SOI,grayscale lithography, etc.) as described above. Alternatively, firstcurved mirror 110 may be formed on, or in, alternative materials thatmay be added to PIC layer 114 for example, second PIC layer substrate122 may be substantially transparent and first curved mirror 110 may beformed according to aspects described herein with respect to transparentsubstrates. Additionally or alternatively, as another example, secondcurved mirror 112 may be formed substantially according to backsidecoupling methods as described herein. Further, according to aspects, itis contemplated that first curved mirror 110 may be added to an alreadyexisting PIC substrate. Aspects where the first curved mirror 110 isadded to an existing PIC substrate or PIC layer 114 may be described inmore detail herein with relation to photonic bumps (e.g., with referenceto FIGS. 16-18C).

As described herein, PIC layer may comprise any number of substrates,first curved mirror may be fabricated in, on, or added to, any of thesubstrates of PIC layer. Further, as is described below in more detail,the first curved mirror may be disposed on the backside of any of thesubstrates of the PIC layer. The method of producing such back-sidemirrors, advantages of such backside mirrors, and operation of suchbackside mirrors, is discussed below in more detail.

According to aspects herein, curved mirrors may be fabricated on, addedto, or otherwise integrated with PhotonicPlug layer variously. Referringto FIG. 1 , PhotonicPlug layer 106 may comprise one or more substrates.PhotonicPlug layer 106 may comprise PhotonicPlug substrate 126.PhotonicPlug substrate 126 may be arranged proximate to spacer layer108. Second curved mirror 112 may be fabricated in, fabricated on, orotherwise added to the surface of PhotonicPlug substrate 126, proximateto spacer layer 108.

According to aspects herein, curved mirrors may be fabricated on, addedto, manufactured in, or otherwise integrated with PhotonicPlug layer106. For example, referring to FIG. 1 PhotonicPlug layer 106 maycomprise at least one substrate. The at least one substrate may be, forexample a semiconductor material, for example, silicon dioxide (SiO₂),silica, silicon, or the like, a metal, plastic, and/or polymer, etc.Additionally or alternative, PhotonicPlug layer 106 may comprisemultiple substrates of any number of materials. The substrate may bearranged adjacent to spacer layer 108. Accordingly, second curved mirror112 may be fabricated on the surface of PhotonicPlug substrate 126. Thesecond curved mirror 112 may be fabricated on the surface ofPhotonicPlug substrate variously. For example, second curved mirror 112may be fabricated using, for example, CMOS, SOI, NIL, grayscalelithography, plastic injection, stamping, etc. SOI may be advantageousfor some applications, for example, SOI may be ideal for certain typesof mirrors, though all methods are contemplated. Additionally, accordingto aspects, like first mirror (and first turning mirror) second mirrormay be coated with a layer of dielectric (e.g., metal) to improvereflectivity for specific signal wavelengths.

As described in more detail herein, PhotonicPlug layer 106 may compriseadditional features (e.g., fiber receiving features, below). Thus, it iscontemplated that such features may be fabricated in the same substrateas the second curved mirror 112. Therefore, according to such aspects,the second curved mirror 112 may be fabricated in a substrate ofPhotonicPlug layer 106 at the same time, and using similar processes,that other features are fabricated in the PhotonicPlug layer substrate(e.g., PhotonicPlug substrate 126). Additionally or alternatively, otherfabrication process, methods, and/or techniques (e.g., plasticinjection) may not require or be associated with fabrication at the sametime. Additionally, some fabrication processes, methods, and/ortechniques may use different tooling for the different optical elements(e.g., different tooling for second curved mirror 112 and the turningmirrors 120).

FIG. 6 depicts an example optical coupler 600 according to one or moreaspects of the present disclosure. Referring to FIG. 6 , PhotonicPluglayer 606 may comprise various substrates of varying materials(described below in more detail). Therefore, it is contemplated that thesecond curved mirror 612 may be fabricated in, added to, or otherwiseintegrated with various substrates of the PhotonicPlug layer 606. Forexample, PhotonicPlug layer 606 may comprise two substrates, firstPhotonicPlug substrate 626A and second PhotonicPlug substrate 626B,according to aspects, the first PhotonicPlug substrate 626A may be of afirst material (e.g., metal, or plastic) and may comprise fiberreceiving features to receive optical fibers. Second PhotonicPlugsubstrate 626B may be fabricated of a second material (e.g., siliconsemiconductor material, glass, polymer, etc.) and may be variouslyassembled with, manufactured with, and/or installed with firstPhotonicPlug substrate 626A. Accordingly, second curved mirror 612 maybe fabricated in second PhotonicPlug substrate 626B. The two substrates626A and 626B may be attached to one another using known methods ofattachment (e.g., adhesives, fasteners, clips, NIL, etc.) to provide thefunctionality of the optical coupler. Further, the first PhotonicPlugsubstrate 626A and second PhotonicPlug substrate 626B may comprisemechanical alignment features to ensure proper alignment of the twosubstrates for working conditions (see, for example, mechanicalalignment features of FIGS. 33A-33B).

As described herein, PhotonicPlug layer 606 may comprise any number ofsubstrates, second curved mirror 612 may be fabricated in, on, added to,or otherwise integrated with any of the substrates of PhotonicPlug layer606. Further as described herein, the second curved mirror may bedisposed on the backside of any of the substrates of the PhotonicPluglayer (see, e.g., FIGS. 37-45 describing backside coupling below). Themethod of producing such back-side mirrors, advantages of such back-sidemirrors, and operation of such back-side mirrors, are discussed below inmore detail.

FIG. 7A depicts an example optical coupler according to one or moreaspects of the present disclosure. Referring to FIG. 7A, one or both ofthe first curved mirror 710 and second curved mirror 712 may befabricated in the spacer layer 708. Spacer layer 708 may comprise firstspacer substrate 718A and second spacer substrate 718B (generally spacersubstrate 718) (alternatively first and second spacer substrates 718Aand 718B may be combined into singe spacer substrate). Alternatively, asdescribed spacer layer 708 may comprise no substrates or any number ofsubstrates. As described herein, one or more of the one or more spacersubstrates may be made of a material that is substantially transparentto the wavelength of the optical signal. First and second curved mirrors710 and 712 may be integrated with first and second spacer substrates718A and 718B. For example. Material may be removed from a surface offirst and second spacer substrates 718A and 718B. The material may beremoved such that the desired shape of the first and/or second curvedmirrors 718A and 718B remain. Following material removal, a reflectivelayer (for example illustrated as dashed line by first curved mirror 710and second curved mirror 712), for example a layer of metal, may beadded to (e.g., deposited on) the curved mirror shape, resulting infirst and second curved mirrors 710 and 712 formed in the substantiallytransparent spacer substrate. Alternatively, the shape of first andsecond curved mirrors 710 and 712 may be formed into the spacersubstrates 718A and 718B when the spacer substrates are produced. Forexample, the spacer may be formed with a mold or a stamp. The mold orstamp may comprise the shape of first curved mirror 710 and/or secondcurved mirror 710 in it. After the spacer substrate is molder orstamped, a reflective layer, for example a layer of metal (illustratedas dashed line), may be added to the curved mirror shape resulting in acurved mirror in the spacer substrate. In yet another alternative, oneor more of the spacer substrates may comprise voids. A separate curvedmirror (e.g., metal mirror, semiconductor mirror, etc.) may be disposedin the voids. The separate curved mirrors may be retained in the voidsvariously, including for example being set in epoxy resin or similarwith suitable index of refraction. Additionally, first curved mirror 710and second curved mirror 712 may be fabricated in spacer substrates 718substantially as described herein with respect to backside couplingmethods (see e.g., FIGS. 37-45 ). Curved mirror on glass spacer may befabricated via wafer lithographic processes or via NIL wafer leveloptics process. Spacer substrates 718 may comprise additional featuressuch as addition optical elements or mechanical elements to be matedwith the substrates above and below for accurate placement relative tothe other substrates.

FIGS. 1 and 6 illustrate first curved mirror (e.g., 110 and 610) asbeing integrated with the PIC layer, and second curved mirror (e.g., 112and 612) as being integrated with the PhotonicPlug layer. Sucharrangements are for purposes of illustration only. According toaspects, as will be appreciated in view of the present disclosure, thecurved mirrors may be disposed variously. For example, the first curvedmirror may be integrated with the PIC layer and the second curved mirrormay be integrated with the PhotonicPlug layer. Alternatively, the firstcurved mirror may be integrated with the PhotonicPlug layer and thesecond curved mirror may be integrated with the PIC layer.Alternatively, the first and second curved mirrors may be integrated inthe PIC layer or the first and second curved mirrors may be integratedwith the PhotonicPlug layer. In yet further alternatives, one or both ofthe first and second mirrors may be integrated with the spacer layer.All combinations of the first and second mirror being disposed in acombination of the PhotonicPlug layer, the spacer layer, and the PIClayer are contemplated herein. As described above the discussion of“layers” may be understood to help illustrate aspects of the presentdisclosure.

To facilitate optical interconnection, and desired configurations,additional mirrors may be comprised in optical couplers according to thepresent disclosure. Referring again to FIG. 1 , optical coupler 100 maycomprise a first turning mirror 120. First turning mirror 120 may alsobe referred to as tilted flat mirror herein. The first turning mirror120 may be disposed adjacent to the optical source/drain component(e.g., optical fiber 102). According to aspects herein, the opticalsource/drain component (e.g., optical fiber 102) in conjunction with thefirst turning mirror 120 may be referred to herein as the opticalsource/drain component. The first turning mirror 120 may be positionedto reflect the optical signal 116 such that the signal 116 may propagateaway from the first turning mirror 120 at a predefined angle (e.g., thecenter of the signal may propagate away from the first turning mirror120 at a predefined angle from the center of the signal approaching thefirst turning mirror 120), or toward a predefined spot (e.g., the firstcurved mirror 110). Use of such a first turning mirror 120 may proveadvantageous for a number of reasons. One such advantage may comprisethat ability to variously position the optical source/drain componentwith respect to the curved mirrors. For example, referring to FIG. 1 ,optical fiber 102 may be disposed in a plane that is substantiallyparallel to the planes in which the curved mirrors 110 and 112 aredisposed. Additionally, the optical fiber 102 may be in the same (ordifferent) plane from the second curved mirror 112 and may be in adifferent plane from the first curved mirror 110. This arrangement mayenable many advantages as described herein. The first turning mirror 120may be angled such that it may relay the optical signal 116 between theoptical fiber 102 and the first curved mirror 110. For example, assumingoptical fiber 102 is the source component, the first turning mirror 120may receive (e.g., by light being incent thereupon) the optical signal116 from the optical fiber 102 and direct and reflect the optical signal116 toward the first curved mirror 110. Alternatively, assuming theoptical signal 116 is the drain component, the first turning mirror 120may receive the optical signal 116 from the first curved mirror 110 anddirect and reflect the optical signal 116 toward (e.g., into) theoptical fiber 102. Thus, it may be appreciated that when configuring animplementation of an optical coupler, it may be advantageous toconfigure the mirrors such that the optical signal 116, propagating fromthe first curved mirror 110 to the first turning mirror 120, may befocused toward the first turning mirror 120.

According to the present disclosure, it may be appreciated that theoptical source/drain may be positioned variously with respect to theremainder of the optical coupler. For instance, in the examples of FIGS.1, 6, and 7 , the optical component (e.g., optical fiber) is depicted asbeing placed in a plane that is parallel to the planes of both the firstcurved mirror and the second curved mirror. However, utilizing the firstturning mirror, such optical fibers may be positioned variously. FIG. 8depicts an example optical coupler according to one or more aspects ofthe present disclosure. Referring to FIG. 8 , optical fiber 802A may beplaced at any angle with respect to the vertical plane. First turningmirror 820 may compensate for the angle of the optical fiber 802.Accordingly, the first turning mirror 820 may be oriented for eachapplication, to consider the angle of the optical fiber 802, such thatthe optical signal 816 may be directed at the first first curved mirror810A as desired. Thus, any arrangement of fiber angle 802A and firstturning mirror angle 820 are contemplated herein. Further advantages ofthe present aspects may be appreciated as well. For example, accordingto aspects comprising fiber receiving feature 824A and a first turningmirror 820, these features may be fabricated in a PhotonicPlug substrate826 of PhotonicPlug layer 106 using similar production processes (e.g.,CMOS, NIL, grayscale lithography, etc.). Therefore, these features maybe easily manufactured with accuracy allowing for simplified accurateplacement of the optical fiber 802A with respect to the rest of thecomponents and elements of the optical coupler 800.

Similar to the curved mirrors, the turning mirror may be fabricated on,added to, disposed on, or otherwise integrated with the optical couplervariously. Referring to FIG. 1 , the first turning mirror 120 may befabricated in the PhotonicPlug layer, near the surface of the substratethat is disposed adjacent to the spacer layer 108. The first turningmirror 120 may be fabricated variously. For example, the substrate inwhich the first turning mirror 120 may be fabricated may be asemiconductor material substrate (as described herein). Accordingly, thefirst turning mirror 120 may be fabricated according to the processesdescribed herein (e.g., NIL, SOI, CMOS, etc.). The first turning mirror120 may similarly be coated with a dielectric material, e.g., metal. Theturning mirror may be fabricated at the time of manufacture of thePhotonicPlug substrate 126 or the turning mirror 120 may be added at alater time. Like the curved mirrors, the first turning mirror 120 may bedisposed in any substrate of any layer of the optical coupler.Additionally, although the first turning mirror may interface theoptical signals with the optical source/drain component (e.g., opticalfiber 102), the first turning mirror 120 may be integrated with the samesubstrate as the substrate to which the optical source/drain componentmay be attached, or, alternatively, the first turning mirror 120 may beintegrated with a different substrate, comprising a substrate of adifferent material than the substrate to which the optical source/draincomponent may be attached.

For discussion purposes and/or for purposes of illustration, the opticalelements may be grouped. First optical elements 151 may comprise firstturning mirror 120 and second curved mirror 112. Alternatively, as willbecome clear from the present disclosure, first optical elements 151may, alternatively, only comprise second curved mirror 112. Secondoptical elements 153 may comprise one or more of first curved mirror 110and/or PIC I/O interface elements 128 (e.g., one or more of taperedphotonic bump, turning curved mirror (TCM) photonic bump, PIC I/Owaveguide, grating coupler, etc.).

As described herein, the mirrors of the present disclosure may befabricated in the back-side of a substrate. Such features, and methodsfor producing the same, are described in more detail below withreference to FIGS. 37-45 , and are described in commonly assigned U.S.patent application Ser. No. 17/645,667, and U.S. patent application Ser.No. 17/645,673, both of these applications are herein incorporated byreference in their entireties.

FIG. 9A, depicts a side cross-section view of an example PhotonicPluglayer according to one or more aspects of the present disclosure.Referring to FIG. 9A, PhotonicPlug layer 906 may comprise one or moresubstrates and numerous features. According to aspects, PhotonicPluglayers may have all some or none of the below described features, forexample, some or all of the features described below may be disposed inone or more other layers of an optical coupler. Optical source/draincomponents (e.g., optical fiber 902) may be attached to the opticalcoupler at the PhotonicPlug layer 906. Accordingly, PhotonicPlug layer906 may comprise features to receive, and optionally, retain suchoptical source/drain components.

Referring to FIG. 9A, PhotonicPlug layer 906 may comprise a receivingsubstrate 926A. Receiving substrate 926A may comprise one or more fiberreceiving features 924. Fiber receiving features 924 may comprise one ormore geometric features, for example, V-shaped trenches (e.g.,V-grooves), U-shaped trenches (e.g., U-grooves), through holes, etc.Fiber receiving features 924 may further act as and/or be configuredsimilarly to fiber alignment features, facilitating alignment of theoptical fiber 902 in relation to the first turning mirror 920. Accordingto aspects without the first turning mirror 920, fiber receivingfeatures 924 (e.g., V-groove) may facilitate alignment of the opticalfiber 902 with another optical element (e.g., a first curved mirror inanother component (e.g., a package substrate) or layer of the opticalcoupler). According to aspects, receiving substrate 926A may comprisevarious fiber receiving features 924 and fiber alignment features.According to aspects, fiber receiving features 924 and fiber alignmentfeatures may be considered a void or trench in the receiving substrate926A. Fiber receiving features 924 may be patterned and configuredvariously. For example, fiber receiving features 924 may be patternedand configured as V-grooves, U-grooves, holes, or as other features aswould be understood by persons of ordinary skill in the art. Differentreceiving features 924 may be associated with different advantages. Forexample, V-groove receiving features 924 may additionally set the depthand/or Z-height of the fiber therein with respect to the opticalelements (e.g., turning mirror 920) of the optical coupler. Additionallyor alternatively, once the depth and/or Z-height of the fibers are setby the receiving feature 924 (e.g., V-groove), the spacer (e.g., spacersubstrate 118) may be positioned and/or variously mounted on the fibers.In certain configurations, V-grooves may be advantageously combined withopen receiving feature 924 (e.g., V-grooves). Other features (e.g.,through-holes) may, in certain configurations be advantageously achievedwith closed features. V-grooves (and other receiving features) mayadditionally be achieved with closed receiving features which may beadvantageous for certain configurations as would be understood from thepresent disclosure. Different features may be differently advantageousdepending on configuration considerations and constraints.

FIG. 9B depicts a front cross-section of the example fiber receivingsubstrate 926A of FIG. 9A according to one or more aspects of thepresent disclosure. Referring to FIG. 9B, as discussed herein,PhotonicPlug layer 906 and fiber receiving substrate 926A may compriseone or more fiber receiving features 924 to accept one or more opticalfibers 902. fiber receiving features 924 may be open features whereinthe feature does not entirely enclose the circumference of the opticalfibers therein. FIG. 9C depicts a front cross-section of an examplefiber receiving substrate 926C according to one or more aspects of thepresent disclosure. As an alternative to open receiving features (e.g.,as illustrated in FIG. 9B) referring to FIG. 9C, fiber receivingfeatures 924 may be closed receiving features, wherein the receivingfeature entirely surrounds a circumference of the optical fibers 902.FIG. 9C depicts the closed receiving features as round holes, however,closed receiving features may be variously shaped. For example, closedreceiving features may be V-grooved on one side (e.g., a bottom of theoptical fiber) and rounded on the opposing side (e.g., top of theoptical fiber), V-groove on both sides, diamond shaped, square shaped,triangular shaped, etc.

Referring to FIG. 9A, the fiber receiving features 924 may be fabricatedin the PhotonicPlug layer 906 variously. For example, according toaspects, the fiber receiving features 924 may be fabricated by removingmaterial (e.g., etched) from receiving substrate 926A in the desiredpattern. Alternatively, the fiber receiving features 924 may befabricated by adding material (e.g., via additive manufacturingtechniques, e.g., material deposition) to the receiving substrate in thedesired pattern. If the receiving substrate is a semiconductor material,the fiber receiving features may be fabricated using any of the methodsdisclosed herein, for example, NIL, SOI, CMOS, grayscale lithography,etc. According to alternative aspects, the receiving substrate 926A maybe fabricated and composed of various materials, and may be composed ofmore than one material. For example, fiber receiving substrate 926A maybe composed of metal (e.g., aluminum, steel, copper, alloys, etc.)plastic, other polymers, epoxies, photoresist materials, and the like.Accordingly, the fiber receiving features 924 may be fabricated inreceiving substrate 926A according to methods known to those of ordinaryskill in the art (e.g., milling, stamping, molding, drilling, etching,embossing, cutting, plastic injection etc.) according to the materialused.

As described, receiving substrate 926A and/or fiber receiving features924 may be fabricated of various materials using various processes. Forexample, according to aspects, fiber receiving features 924 may beadditively produced using photoresist materials, for example,epoxy-based photoresist materials (e.g., SU-8). Such additive materialsmay be deposited on one or more different underlying materials, e.g.,silicon, to produce the receiving substrate 926A. Alternatively, theentire receiving substrate 926A, or portions thereof, may be produced ofsuch additive materials (e.g., SU-8). Such additive materials may belayer deposited (e.g., UV positive or negative photoresist).Alternatively, the fiber receiving features 924 may be producedvariously. For example, fiber receiving features 924 may be producedutilizing hot-embossing. For example, a material (e.g., thermoplastic,or other polymers) may be deposited. A stamp with the inverse of thedesired receiving feature 924 may be applied to the surface of thematerial (e.g., thermoplastic). Pressure and heat may be applied to thestamp followed by a cooling step producing the desired receiving feature924. Alternatively, fiber receiving features 924 may be producedutilizing metal stamping or similar processes.

Optical fibers 902 may be retained in receiving features 924 variously.For example, the optical fibers 902 may be retained in the receivingfeatures with adhesive, epoxy, resins, etc. According to such aspects,it may be advantageous to use an epoxy, resin or adhesive with certainoptical properties (e.g., index matching, as described herein). Forexample, an epoxy or resin may be selected based on its index ofrefraction to allow light to propagate from the optical fiber into thecoupler as would be understood by a person of ordinary skill in the art(as described in more detail herein). According to aspects comprisingopen receiving features 924, a portion of the circumference of theoptical fibers 902 may extend beyond the surface of the receivingsubstrate 926A. Accordingly, the fibers may be retained in place byapplying pressure to the exposed circumference of the optical fibers 902and the top surface of the receiving substrate 926A in opposingdirections. For example, as described in more detail herein, clip 946(or other retaining structure) may be affixed to the receiving substrate926A around the optical fibers 902. Clip 946 may apply a force to theoptical fiber toward the top of receiving substrate 926A, and may applya force to the top of receiving substrate 926A in an opposing directionwhich may assist retention of the optical fibers 902 in the receivingsubstrate 926A.

Referring to FIG. 9C, according to further aspects, the optical fibers902 may be inserted into receiving features 924 that are closed (e.g.,holes). According to such aspects, optical fibers 902 may similarly beretained within the receiving substrate 926C variously. For example,like the open receiving features, adhesives, epoxies, resins, etc. (withappropriate indices of refraction) may be similarly used to retainoptical fibers 902 in the closed receiving features. Additionally oralternatively, according to such aspects, retaining members (e.g.,clips) may be used that apply a force to the optical fibers 902 alongthe axis of the optical fiber 902 and into the receiving feature 924.Thereby, the optical fibers 902 may be retained in the closed receivingfeatures 924 (such a method may be employed in open receiving featuresas well). The optical fibers 902 may be retained in the receivingfeatures 924 variously as would be understood by persons of ordinaryskill in the art.

Referring to FIG. 9A, PhotonicPlug layer 906 may comprise receivingsubstrate 926A and second PhotonicPlug layer substrate 926B. SecondPhotonicPlug layer substrate 926B may comprise the second curved mirror912. According to alternative aspects, PhotonicPlug layer 906 may onlycomprise one substrate which may comprise receiving features 924 andsecond curved mirror 912. PhotonicPlug layer 906 of FIG. 9A isillustrated has having multiple substrates that are vertically cut andhorizontally separable. According to alternative aspects however,various substrates of PhotonicPlug layer (and spacer layer, and PIClayer) may be variously cut and variously separable (e.g., horizontallycut and vertically separable). Any combination of cut and separabilitybetween substrates of an optical coupler layer is contemplated herein.According to aspects comprising a plurality of substrates inPhotonicPlug layer 906, the substrates may be oriented and packagedvariously as would be understood by persons of ordinary skill in the artand as may be appreciated from the present disclosure. Additionally,substrates may comprise alignment features 950 to assist in aligningsubstrates during assembly and/or installation (as described in moredetail herein).

While the accommodation for multiple fibers in a side-by-side (e.g.,lateral) arrangement has been illustrated (see, e.g., FIGS. 2, 9B, and9C) it is also contemplated herein that PhotonicPlug layers may comprisestacked fibers (e.g., vertically arranged). FIG. 10A depicts a crosssection of an example stacked optical coupler 1000A according to one ormore aspects of the present disclosure. The example stacked opticalcoupler 100A may comprise optical fibers arranged in a stacked (e.g.,vertical) configuration. The terms “side-by-side,” “lateral,” “stacked,”and “vertical” are for purposes of illustration only. It should beunderstood that the stacked optical couplers may be used and orientedvariously in use, as such, that which is described as vertical inrelation to the present FIGS. may be arranged variously in use (e.g.,the configuration of FIG. 10A may be rotated 90° in use such that the“stacked” configuration becomes a “lateral” or “side-by-side”configuration. Therefore, these terms (e.g., “side-by-side,” “lateral,”“stacked,” and “vertical”) are not intended to be limiting but arecomprised for purposes of illustration only.

Referring to FIG. 10A, stacked optical coupler 1000A may opticallyconnect first optical fiber 1002A and second optical fiber 1002B tofirst PIC 1004A and second PIC 1004B respectively. first optical fiber1002A may be set at a first height h1 in the receiving substrate. Secondoptical fiber may be disposed at a second height h2 in the receivingsubstrate 1026. Additionally, the first and second optical fibers 1002Aand 1002B may be stepped from one another. The optical fibers 1002 maybe stepped, e.g., first optical fiber 1002A may be set at a first depthd1 in receiving substrate 1026 and second optical fiber 1002B may be setat second depth d2 in receiving substrate 1026. (First and secondoptical fibers may be disposed in a single substrate or multipleseparate substrates). First first turning mirror 1020A may be disposedproximate to first optical fiber 1002A and second first turning mirror1020B may be disposed proximate to second optical fiber 1002B. Further,each optical fiber 1002A and 1002B may comprise an associated firstcurved mirror 1010A and 1010B, and associated second curved mirror 1012Aand 1012B. While FIG. 10A depicts the optical fibers 1002A and 1002B,first turning mirrors 1020A and 1020B, and second curved mirrors 1012Aand 1012B as all being disposed in the same substrate, it iscontemplated that each of these elements may be disposed in their ownsubstrates or may be disposed in any combination in any combination ofsubstrates. Further, while FIG. 10A shows a PhotonicPlug layer 1006 andreceiving substrate 1026 that includes two stacked optical fibers 1002,it is contemplated herein that PhotonicPlug layer 1006 and/or receivingsubstrate 1026 may comprise any number of stacked optical fibers 1002.Additionally, FIG. 10A depicts optical fibers 1002 as the source/drainoptical component, however, it is contemplated herein that opticalcouplers (e.g., stacked optical coupler 1000A) may optically couple anysource/drain optical components in any combination (e.g., PIC-to-PIC,PIC-to-waveguide, etc.). Additionally, FIG. 10A depicts two PICs assource/drain optical components, however, it is contemplated herein thatoptical couplers may optically couple any optical components.

Referring to FIG. 10A, the second optical signal 1016B, (e.g., coupledbetween the second optical fiber 1002B and second PIC 1004B), taken inthe fiber-to-PIC direction, may enter the stacked optical coupler 1000Afrom the second optical fiber 1002B. The second optical signal 1016B maybe interfaced by the second first turning mirror 1020B, and may bedirected from, and reflected by, the second first turning mirror 1020B,to the second first curved mirror 1010B. Accordingly, the second opticalsignal 1016B may propagate through (e.g., traverse) the first opticalfiber 1002A (and any additional optical fibers) disposed relativelybelow the second optical fiber 1002B. Further, according to aspects, theoptical signal may propagate through a portion of the substrate(s) ofthe PhotonicPlug layer. Subsequently, the second optical signal 1016Bmay propagate through the stacked optical coupler 1000A substantially asdescribed in relation to the signal diagrams herein. For example, thesignal may propagate through the spacer layer 1008 to second firstcurved mirror 1010A, second first curved mirror 1010A may substantiallycollimate, reflect the second optical signal 1016B and direct thesubstantially collimated optical signal to the second second curvedmirror 1012B. The second second curved mirror 1012B may substantiallyfocus the second optical signal 1016B, may reflect the second opticalsignal 1016B, and may direct the substantially focused optical signal atthe second PIC I/O interface 1028B. The first optical signal 1016A maypropagate similar to the above, though the first optical signal 1016Amay not propagate through (e.g., traverse) another optical fiber.However, as described above, it is contemplated that stacked opticalcoupler may comprise any number of stacked source/drain opticalcomponents (e.g., optical fibers), therefore, the optical signals to andfrom a higher optical component, may propagate through all lower opticalcomponents. Additionally, FIG. 10B shows an example configuration withtwo separate PICs 1004A and 1004B. Alternative configurations maycomprise a single PIC. The single PIC may comprise multiple PIC I/Ointerfaces (e.g., first and second PIC I/O interfaces 1028A and 1028B).

FIG. 10A, depicts an example stacked optical coupler for stacked opticalfibers with a shallower depth of the second optical fiber (e.g., thehigher optical fiber) than the first optical fiber (e.g., lower opticalfiber). However, it is contemplated herein that the step of the opticalfibers may be inverted. FIG. 10B depicts an example alternative stackedoptical coupler 1000B according to one or more aspects herein. Referringto FIG. 10B, the first optical fiber may be disposed at a depth d1 andsecond optical fiber may be disposed at a depth d2, where d2 is deeperthan d1. Accordingly, the higher optical fibers of the stacked opticalfibers may overhang the lower optical fibers. Thus, FIG. 10B, depicts anexample stacked optical coupler 1000B wherein the optical signal to andfrom the higher optical fiber (e.g., second optical fiber 1002B) may notpropagate through, or traverse, the lower optical fiber (e.g., firstoptical fiber 1002A). According to such aspects, the optical signals maypropagate through the stacked optical coupler substantially asillustrated and described with respect to FIG. 10A but may not propagatethrough lower optical fibers.

Still referring to FIG. 10B, an inverse stepped stacked optical fiberarrangement may use a first receiving substrate 1004A and a secondreceiving substrate 1004B substrate. Accordingly, first receivingsubstrate 1004A may comprise first fiber receiving feature 1006A toreceive and align the first optical fiber 1002A. Additionally, thesecond receiving substrate 1004B may comprise a second receiving feature1006B to receive and align the second optical fiber 1002B. According toaspects, the first receiving substrate 1004A, or a portion thereof, aswell as spacer of spacer layer 1008 may be substantially transparent toat least a range of wavelengths of light (e.g., the wavelength of theoptical signal).

FIGS. 10A and 10B are two-dimensional, cross-sectional illustrations ofexample stacked optical couplers. However, in three dimensions, examplestacked optical couplers may also comprise side-by-side optical fibers.Accordingly, FIG. 10C depicts a front cross-section view of an examplereceiving substrate for a stacked optical fiber coupler. Referring toFIG. 10C. stacked receiving substrate 1026 may accommodate first row ofoptical fibers (e.g., first optical fiber ribbon 1074A) and second rowof optical fibers (e.g., second optical fiber ribbon 1074B). Accordingto such aspects, the multiple ribbons may be stacked directly on top ofone another (e.g., the optical fiber ribbon 1074A may be disposedsubstantially directly above second optical fiber ribbon 1074B).Alternatively, the multiple optical fiber ribbons 1074A and 1074B may belaterally off-set from one another (e.g., each optical fiber of firstoptical fiber ribbon 1074A may be disposed substantially above in inbetween each optical fiber of second optical fiber ribbon 1074B).Optical couplers (e.g., stacked optical couplers 1080A and 1000B) mayincorporate any number of optical fiber ribbons. The optical fiberribbons may be positioned variously in relation to one another as wouldbe understood by persons of ordinary skilled in the art considering thepresent disclosure. FIGS. 10A-10B depicts first and second opticalfibers 1002A and 1002B as being coupled to two different PICs 1004A and1004B, respectively. Accordingly, each PIC is depicted as comprising aPIC I/O interface 1028A and 1028B (which may comprise, for example,amongst other things, PIC I/O waveguides). It is also contemplatedherein that first and second optical fibers 1002A and 1002B may beconnecter to two different PIC I/O interfaces of the same PIC (forexample one for transmission of optical signals and one for reception ofoptical signals).

FIG. 11 depicts an example dual-sided optical coupler. Referring to FIG.11 , PhotonicPlug layer 1106 may accept optical source/drain componentsfrom opposing directions. First optical fiber 1102A may be coupled to,and enter at, a first side of the optical coupler 1100. Second opticalfiber 1102B may be coupled to, and enter at, a second side of theoptical coupler, from a second direction that is substantially opposedto the first direction. First optical signal 1116A and second opticalsignal 1116B may propagate through the optical coupler substantially asdescribed with relation to optical couplers (e.g., with relation toFIGS. 1-5C). FIG. 11 depicts the optical coupler 1100 as accepting asingle optical fiber 1102 (e.g., single row of optical fibers in threedimensions) on either side. However, it is contemplated herein that theoptical coupler can be a stacked optical coupler (as described inrelation to FIGS. 10A-10C) as well. Thus, it is contemplated thatoptical coupler may comprise two or more optical fiber ribbons stackedper side of the coupler. Additionally, FIG. 11 depicts a two-dimensionalcross-section of dual-sided optical coupler 1100. Additionally oralternatively, dual-sided optical coupler 1100 may also comprise aplurality of optical fibers in a side-by-side arrangement onmultiple-sides of the dual-sided optical coupler 1100. Any number ofoptical fiber ribbons per side is contemplated herein, and the opposingsides may or may not comprise the same number of optical fiber and mayor may not comprise the same number of optical fiber ribbons.Additionally, FIG. 11 depicts first and second optical fibers 1102A and1102B as being coupled to two different PICs 1104A and 1104B,respectively. Accordingly, each PIC is depicted as comprising a PIC I/Ointerface 1128A and 1128B (which may comprise, for example, amongstother things, PIC I/O waveguides). It is also contemplated herein thatfirst and second optical fibers 1102A and 1102B may be connecter to twodifferent PIC I/O interfaces of the same PIC (for example one fortransmission of optical signals and one for reception of opticalsignals).

Example optical couplers have been illustrated herein (e.g., withreference to FIGS. 1, 2, 9, 10A-10B, and 11 ) with optical fibersarranged substantially parallel with the substrates of the underlyinglayers. FIG. 12A depicts an example optical coupler 1200 according toone or more aspects of the present disclosure. Referring to FIG. 12A,optical couplers may accept optical fibers 1002 at varying angles withrespect to the underlying substrates. Referring to FIG. 12A, receivingsubstrate 1226A may receive optical fibers 1202 at an angle relative tothe receiving substrate 1226A and/or PhotonicPlug layer 1206. Fiberreceiving features 1224A and 1224B may be fabricated in receivingsubstrate 1226A at angles with respect to the receiving substrate 1226A.Optical fibers 1202 may be placed, and secured, in the receivingfeatures 1224 at the predefined angles of the receiving features 1224.The angle of the optical fibers 1202 may be selected based on thedesired angles of propagation of the signal path. For example, assumingan example first angle of propagation, a, (e.g., as illustrated in FIG.3 ) is to be set at 8° from a vertical plane. Accordingly, receivingfeatures 1224 may be fabricated in, and optical fibers 1202 may bereceived in, the receiving substrate 1226A at the desired first angle ofpropagation, a. First curved mirrors 1210 may be situated in directlines from the angled optical fibers 1202. Thus, according to suchaspects, first turning mirrors may be omitted from the optical coupler1200.

Referring to FIG. 12A, angled fiber receiving features 1224 may befabricated through substantially all of the receiving substrate 1226Asuch that the ends of the optical fibers 1202 may terminate near,practically abut, or abut, the spacer below. Additionally oralternatively, fiber receiving features 1224 may be fabricated throughonly a portion of the receiving substrate 1226A. According to suchaspects, the optical signals 1216 may propagate through the receivingsubstrate 1226A as described herein. Such receiving substrates maycomprise, for example, silicon material through which optical signalsmay propagate (e.g., silicon materials that are substantiallytransparent to the optical signal wavelength). Accordingly, one or moreanti-reflective layers may be deposited (e.g., coated) or otherwiseplaced on one or more surfaces of the receiving substrate to ensureproper index matching and/or to avoid increased scattering and/orincreased signal attenuation. FIG. 12B depicts an example receivingsubstrate 1226B according to one or more aspects of the presentdisclosure. Referring to FIG. 12B, some or all of the fiber receivingfeatures 1224 may stop at a specified depth in the receiving substrate1226B, and a through hole 1242 may continue through the rest of thereceiving substrate 1226B in which optical signal may propagate.According to aspects, the through holes 1242A and 1242B may be filledwith a substance (e.g., epoxy) with a suitable index of refraction(e.g., an index of refraction substantially similar to that of thespacer, according to aspects comprising a spacer). Additionally, FIG.12B depicts first and second optical fibers 1202A and 1202B as beingcoupled to two different PICs 1204A and 1204B, respectively.Accordingly, each PIC is depicted as comprising a PIC I/O interface1228A and 1228B (which may comprise, for example, amongst other things,PIC I/O waveguides). It is also contemplated herein that first andsecond optical fibers 1202A and 1202B may be connecter to two differentPIC I/O interfaces of the same PIC (for example one for transmission ofoptical signals and one for reception of optical signals).

Referring to FIG. 8 , as described optical fibers 802 may be placed atan angle relative to the PIC 804 and underlying substrates, andaccording to aspects, optical fibers 802 may be placed at an angle thatis different from the first angle of propagation, α. For example, assumethat the example desired first angle of propagation is 8° from thenormal. The optical fibers 802 may be secured to the receiving substrate826 at an angle different from 8° (e.g., 45 degrees from the vertical).Accordingly, turning elements (e.g., first turning mirror 820, turninglenses) may be implemented to achieve the example desired angle ofpropagation (e.g., 8° from a vertical plane). Thus, it can be seen thataccording to the present disclosure, optical fibers 802 may be angledvariously with respect to the remainder of the optical coupler.

Referring again to FIG. 12A, as can be appreciated from the presentdisclosure, such an example configuration may allow for dense packing ofoptical fibers and an increase in optical I/O connections. While FIG.12A depicts a plurality of optical fibers 1202 in a two-dimensionalcross-sectional plane, it is contemplated herein that the same couplermay allow for a plurality of fibers in a plane that is transverse to thecross-sectional plane depicted in FIG. 12A. For example, each of firstoptical fiber 1202A and second optical fiber 1202B may be one fiber in aribbon of optical fibers connected to optical coupler 1200. Therefore,similar to that which is illustrated in FIGS. 8A-8C, optical coupler mayaccommodate multiple rows of optical fiber ribbon that may beincorporated with optical coupler 1200 at an angle with respect to theunderlying substrates. Additionally, such an arrangement may beunderstood as a two-dimensional matrix of optical fibers connected tothe optical coupler (as seen from a view above the optical coupler).While FIG. 12A depicts two optical fibers (e.g., first and secondoptical fibers 1202A and 1202B) in the same cross-sectional plane (e.g.,two optical fiber ribbons connected to optical coupler), optical couplermay be configured to accommodate any number of optical fibers in thesame cross-sectional plane (e.g., 6 optical fiber ribbons connected tothe optical coupler).

As described above, it is contemplated herein that the PhotonicPluglayer 1206 may comprise any number of substrates and may be fabricatedof a combination of multiple materials (silicon, silicon oxide, metal,plastic, etc.). Where the PhotonicPlug layer 1206 is made of certainmaterials of lower thermal conductivity (e.g., silicon) external heatsinks may be desired according to configurations as described in moredetail hereinbelow. However, where the PhotonicPlug layer 1206comprises, or is fabricated of, material with a requisite thermalconductivity (e.g., metal, aluminum, steel, etc.), the PhotonicPluglayer itself may act as and/or be configured similarly to a thermal heatsink. Accordingly, an external heatsink may be forgone according to suchaspects resulting in a reduced size of the optical coupler package. Forexample, referring to FIG. 12A, the receiving substrate 1226A may beconstructed of aluminum, as such, the receiving substrate 1226A may beof sufficient thermal conductivity such that an additional separate heatsink may not be required. Further yet, heat sink fins (e.g., pin fins,louvered fins, perforated fins, etc.) may be integrated with thePhotonicPlug layer 12026 (either as apart of receiving substrate 1226 orseparate from receiving substrate 1226) to further improve the thermalmanagement at the PhotonicPlug layer 1206. For example, receivingsubstrate 1226A may comprise heat exchange features (e.g., fins) in thespace between the first optical fiber 1202A and second optical fiber1202B (and in three dimensions, in between the first row of opticalfibers (first optical fiber ribbon) and second row of optical fibers(second optical fiber ribbon)). Thus, dense optical I/O may be realizedand improved with a single optical coupler.

As described herein, optical coupler may comprise a spacer layer.Referring to FIG. 1 , spacer layer 108 may be implemented to realize oneor more of numerous functions. For example, spacer layer 108 may beimplemented to space (e.g., distance) optical coupler components and/orelements as desired. For example, it may desirous to space first curvedmirror 110 from second curved mirror 112 according to example designspecifications. Additionally, it may be desirous for optical signal 116to propagate through optical coupler while minimizing optical losses. Tothat end, according to aspects, spacer layer 108 may comprise one ormore spacer substrates 118 of material that is substantially transparentto the wavelength of the optical signal (e.g., glass, epoxy, silicon,etc.). Additionally, it may be advantageous to fabricate spacersubstrate 118 out of substantially non-conductive materials. Such highlytransparent and substantially non-conductive materials may comprise, forexample, glass, polymethylsiloxane, epoxy, or other similarindex-matching materials etc. As will be described herein in more detail(e.g., with respect to FIG. 34B), electrical elements, for example,electrical pads, electrical traces, electrical through vias, etc. may beadded to the spacer 118 that may be substantially non-conductive.Additionally, the spacer substrate 118 may be a semiconductor materialas will be described herein in more detail.

It should be noted that layers of the optical coupler may not be uniformand may not have uniform interfaces. For example, substrates of thePhotonicPlug layer 106 may extend into the spacer layer 108, andsubstrates of the spacer layer 108 may extend into either thePhotonicPlug layer 106 and/or the PIC layer 114. The description ofPhotonicPlug layer 106, spacer layer 108, and PIC layer 114 is intendedfor purposes of illustration only and is described as such only forclarity of discussion. PhotonicPlug layer 106, spacer layer 108, and PIClayer 114 are not considered discrete layers with discrete elements andfunctionality, rather, the functionality as described herein withrelation to one layer (e.g., receiving substrate in the PhotonicPluglayer), may similarly be accomplished by another layer (e.g., spacerlayer and/or PIC layer may comprise fiber receiving features to receiveoptical fibers).

Spacer substrate 118 may be variously attached to the PhotonicPlug layer106 substrates and/or the PIC layer 114 substrates according to aspects.Accordingly, spacer 118 may be coupled to PhotonicPlug layer substratesand/or PIC layer substrates with bonding agents, for example adhesives,epoxies, resins, etc. Accordingly, it may be advantageous to selectbonding agents with suitable optical characteristics (e.g., index ofrefraction), and mechanical characteristics as would be understood by aperson of ordinary skill in the art and as described herein in moredetail. For example, when selecting a material to be used for the spacersubstrates, it may be advantageous to select a bonding agent withdesirable thermal characteristics (e.g., thermal expansion) to retainoperability and longevity of the optical coupler elements andcomponents.

FIG. 13 depicts an example lensed optical coupler 1300 according to oneor more aspects of the present disclosure. As will be appreciated bypersons of ordinary skill in the art, aspects of the preset disclosuremay be practiced with lenses. For example, the collimation and focusingof the optical signal may, like curved mirrors, similarly be achievedwith lenses, for example, a Fresnel lens, convex lens, or silicon lens.Thus, such lenses may be implemented in conjunction with mirrors (e.g.,flat mirrors) to achieve similar results to those which may be achievedwith curved mirrors. According to such aspects, the lenses may beimplemented to transform the optical signal, for example, to collimateand focus the optical signal, and the mirrors may be used to reflect anddirect the optical signal. Referring to FIG. 13 , lensed optical coupler1300 may comprise first collimating/focusing lens 1330 and secondcollimating/focusing lens 1332. The first and secondcollimating/focusing lenses 1330 and 1332 may be formed in spacer 1318of spacer layer 1308. Additionally, lensed optical coupler 1300 mayfurther comprise first directing mirror 1334 and second directing mirror1336. First and second directing mirrors 1334 and 1336 may besubstantially flat mirrors. Additionally, first and second directingmirrors 1334 and 1336 may be disposed at predefined angles with respectto the underlying substrate in order to direct the optical signal 1316along the signal path as desired according to example configurations.

The optical signal 1316 may propagate through the lensed optical coupler1300, and may be manipulated/transformed by the optical couple coupler1300, as follows. Assuming the optical signal 1316 originates in thelensed optical coupler 1300 from the optical fiber 1302 (e.g., theoptical fiber acts as the source), the optical signal 1316 may enter thelensed optical coupler 1300 from the optical fiber 1302 toward the firstturning mirror 1320. First turning mirror 1320 may reflect the opticalsignal 1316 toward the first collimating/focusing lens 1330 and thefirst directing mirror 1334. The first collimating/focusing lens 1330may substantially collimate the optical signal 1316. The first directingmirror 1334 may receive and reflect the substantially collimated opticalsignal 1316 toward the second directing mirror 1336. The seconddirecting mirror may receive the substantially collimated optical signal1316 from the first directing mirror 1334 and may reflect thesubstantially collimated optical signal 1316 toward the secondcollimating/focusing lens 1332 and the PIC I/O interface 1328. Thesecond collimating/focusing lens 1332 may focus the optical signal 1316toward the PIC I/O interface 1328. The PIC I/O interface 1328 mayreceive the focusing optical signal 1316. As will be appreciated, thesame scheme may operate in reverse (e.g., where the PIC I/O interface1328 acts as the source and the optical fiber 1302 acts as the drain).Thus, it can be appreciated that the interconnection schemes of thepresent disclosure may be accomplished with a combination of lenses andmirrors.

Collimating/focusing lenses 1330 and 1332 may be disposed in the spacerlayer 1308. This may be advantageous because, as described above, thespacer substrate 1318 of spacer layer may be fabricated of substantiallytransparent materials. As such, spacer layer 1308 may lend itself to theincorporation of optical lenses. For example, first collimating/focusinglens 1330 may be formed in first spacer substrate 1318A and secondcollimating/focusing lens 1332 may be fabricated in second spacersubstrate 1318B. Each of the first and second collimating/focusinglenses 1330 and 1332 may be formed as a part of the spacer substrates1318A and 1318B (e.g., via NIL, CMOS, etc.). Alternatively, first andsecond collimating/focusing lenses 1330 and 1332 may be fabricatedseparately from the spacer substrates 1318A and/or 1318B and may beadded to the spacer substrates 1318A and/or 1318B. While FIG. 13 depictsboth collimating/focusing lenses 1330 and 1332 as being incorporatedwith spacer layer 1308, one or both of the collimating/focusing lenses1330 and 1332 may be incorporated with any layer of the lensed opticalcoupler 1300. For example, according to aspects, first and/or secondcollimating/focusing lenses 1330 and 1332 may be incorporated withPhotonicPlug layer 1306. Alternatively, first and/or secondcollimating/focusing lenses 1330 and 1332 may be incorporated with PIClayer 1314. Any combination of the above is considered herein.Additionally, any or all of the PhotonicPlug substrate 1326, the firstspacer substrate 1318A, the second spacer substrate 1318B, and/or thePIC substrate 1322 may comprise alignment marks and/or features toensure proper alignment of the optical elements of the differentsubstrates. Additionally, any or all of the PhotonicPlug substrate 1326,the first spacer substrate 1318A, the second spacer substrate 1318B,and/or the PIC substrate 1322 may comprise mechanical alignment features(e.g., as described herein with respect to FIGS. 33A and 33B) (e.g.,pillars, and holes, plugs and sockets, etc.) to assist mechanicalassembly and accuracy of the substrates of the optical coupler 1300.

FIG. 13 depicts first collimating/focusing lens 1330 as being disposedupstream from the first directing mirror 1334 and the secondcollimating/focusing lens 1332 as being disposed downstream from thesecond directing mirror 1336. However, according to aspects, firstcollimating/focusing lens 1330 may be disposed upstream or downstreamfrom the first directing mirror 1334, and second collimating/focusinglens 1332 may be disposed upstream or downstream from the seconddirecting mirror 1336 without changing the principles of operationherein. Thus, any combination of collimating/focusing lenses 1330 and1332 either upstream or downstream from first and second directingmirrors 1334 and 1336 is contemplated herein.

FIG. 13 depicts a lensed optical coupler 1300 with twocollimating/focusing lenses 1330 and 1332 and two directing mirrors 1334and 1336. However, according to aspects, lenses and directing mirrorsmay be used in conjunction with curved mirrors. Thus, in FIG. 13 ,either first collimating/focusing lens 1330 and first directing mirror1334 may be replaced by a curved mirror, or second collimating/focusinglens 1332 and second directing mirror 1336 may be replaced by a curvedmirror. The curved mirror may be disposed in any layer as describedelsewhere herein. Additionally, FIG. 13 depicts the lensed opticalcoupler 1300 as having a first turning mirror 1320. However, asdescribed herein, according to aspects, the optical coupler may notcomprise a first turning mirror 1320.

Referring to FIG. 7A, as described, spacer layer 708 may comprise one ormultiple substrates (e.g., spacer substrates 718A and 718B).Alternatively, substrates of spacer layer 708 may be omitted for emptyspace in place of one or more substrates. An anti-reflective layer 752(e.g., coating) may be used at some or all spacer layer substrateinterfaces. Such anti-reflective layers 752 may alleviate issuesconcerning mismatch in the index of refraction of material as theoptical signal propagates from one medium to another and may alleviatereflection, attenuation, and/or scattering of the optical signal at suchinterfaces. Anti-reflective layer 752 may comprise single-layer ormulti-layer applications. Examples of anti-reflective layer 752 mayinclude Magnesium Fluoride, other fluoropolymers, Silicon Nitride,Titanium Dioxide or any other suitable anti-reflective layers 752 knownto persons of ordinary skill in the art. Additionally, anti-reflectivelayers may be applied to any substrate interface of the optical couplersherein. As an example, assume the spacer layer comprises two substrates718A and 718B. According to such aspects, an anti-reflective layer 752may be applied to the PhotonicPlug layer-first spacer substrateinterface. Additionally or alternatively, anti-reflective layer(s) maybe applied to the first spacer substrate-second spacer substrateinterface. Anti-reflective layers may be applied either to one substrateat an interface or to multiple substrates at an interface. Additionally,it should be appreciated that alignment features may be added at one ormore of all substrate interfaces. For example, alignment marks may beadded to one or more of the substrates for assembly machine visualalignment. Additionally, as described hereinbelow (e.g., with respect toFIGS. 33A-33B) mechanical alignment features (e.g., pillars and holes,plugs and sockets, etc.) may be added to one or more of the substratesof the optical coupler 700A to ensure mechanical alignment of thesubstrates and optical elements.

FIG. 7B shows an example optical coupler 700B according to one or moreaspects of the present disclosure. FIG. 7A depicts an example opticalcoupler 700B with a split spacer being split in the horizontaldirection. It should be understood that the spacer 718 (and all othersubstrates) may be similarly split in the vertical direction. Forexample, FIG. 7B depicts an optical coupler 700B with a spacer 718 thatis split into three portions (e.g., 718A, 718B, and 718C). spacers andother substrates may be split for various purposes as would beunderstood by persons of ordinary skill in the art. For example, spacermay be split into multiple parts having multiple materials. For example,spacer parts 718A and 718C may be one material (e.g., silicon) whilespacer part 718B may be another material (e.g., glass). Additionally,spacer 718 and other substrates may be variously split to facilitateassembly. As described above, alignment features are contemplated at allsubstrate interfaces.

Additionally, referring to FIG. 7B, the first curved mirror 710 and/orthe second curved mirror 712 may be angled with respect to therespective underlying substrate. For example, the first curved mirror710 may be at a first angle, δ, with respect to the PIC substrate 722.The first angle, δ, may be any angle, for example, from 0° to 90°.Additionally or alternatively, the second curved mirror 712 may be at asecond angle, F, with respect to the PhotonicPlug substrate 726. Thesecond angle, F, may be any angle, for example, from 0° to 90°.Depending on the configuration of the optical coupler 700B, the firstangle, δ, may be the same as the second angle, F. Alternatively, thefirst angle, δ, and the second angle, F, may be different. Accordingly,different coupler configurations may be achieved considering differentdesign parameters.

FIG. 14 depicts an example optical coupler 1400 according to one or moreaspects of the present disclosure. Referring to FIG. 14 , opticalsource/drain component may be connected to, or otherwise integratedwith, the optical coupler 1400 at the spacer layer 1408. Accordingly,optical fiber 1402 may be coupled to the optical coupler 1400 at thespacer layer 1408. Spacer substrate 1418 may comprise fiber receivingfeatures 1424 substantially as described with respect to receivingfeatures of FIGS. 9A-9C. The methods of coupling may substantiallycomply with the methods of coupling optical fibers to the opticalcoupler described elsewhere herein. Referring to FIG. 14 , where opticalfiber 1402 is coupled to the optical coupler 1400 at the spacer layer1408, the spacer substrate 1418 may further comprise first turningmirror 1420 (according to aspects comprising first turning mirror).Additionally, first curved mirror 1410 and/or second curved mirror 412may additionally or alternatively be incorporated with the spacersubstrate 1418 and/or the spacer layer 1408.

Similar to that which is described with respect to FIGS. 7A and 7B,first turning mirror 1420 in spacer substrate 1418 may be fabricatedvariously. According to aspects, spacer substrate 1418 may be fabricatedof substantially transparent materials (or material that issubstantially transparent to the optical signal 1416). Such materialsmay be formed variously depending on the material chosen, as would beappreciated by those of ordinary skill in the art. For example, a spacersubstrate 1418 of a polymer may be hot embossed or additivelymanufactured as described elsewhere herein. Additionally oralternatively, spacer substrate 1418 may be fabricated of glass. Assuch, spacer substrate 1418 may be molded, slumped, ground, polished,etc. to create the desired spacer substrate 1418 shape. Accordingly, theshape for fiber receiving feature 1424 may be fabricated insubstantially transparent spacer substrate 1418. Similarly, the shape offirst turning mirror 1420 may be produced in substantially transparentsubstrate. Subsequently, a reflective layer may be added (e.g.,deposited, coated, etc.) on the spacer substrate 1418 in the area of thefirst turning mirror 1420 to create the first turning mirror 1420 asdesired. Optical signals 1416 may then propagate through the opticalcoupler 1400, from fiber-to-PIC and from PIC-to-fiber substantially asdescribed elsewhere herein. Additionally or alternatively, spacersubstrate may be fabricated of silicon. Accordingly, first turningmirror 1420, first curved mirror 1410, and second curved mirror 1412 maybe fabricated substantially as described elsewhere herein.

Referring to FIG. 15 , the optical coupler of the present disclosure mayadditionally be connected to, or otherwise facilitate connection to oneor more additional electrical and/or optical components. For example,the optical coupler 1500 may facilitate connection to various electricalcomponents, for example, electronic integrated circuits (EIC),application-specific integrated circuits (ASIC), application-specificstandard products (ASSP), a system-on-a-chip (SOC), microprocessors,microcontrollers, GPUs, digital signal processors (DSP), switches, andthe like. Interposer spacer substrate 1518 may comprise one or moreelectrical through-hole vias (e.g., through glass vias (TGVs), throughsilicon vias (TSVs)). Electrical through-hole vias (e.g., TGVs and/orTSVs) may be considered passive electrical elements for facilitatingconnection of electrical components. And interposer spacer substrate1518 may additionally or alternatively comprise one or more opticalthrough-die vias (OTDVs) (which may be referred to herein, for example,as Optical Through Glass Vias and/or Silicon Optical Vias). OTDVs may beconsidered optical components for facilitating connection of opticalcomponents. For example, as described in more detail herein, it may beadvantageous to package optical components with electrical components,in the same system as electrical components, in proximity to electricalcomponents, and/or on the same substrate as electrical components. Forexample, such arrangements may be advantageous where high-speed opticalconnections are connected to electrical computing elements (e.g.,electrical ASICs, electrical processors, electrical memories, electricalswitches, etc.). Accordingly, a single spacer may facilitate optical andelectrical connection.

For example, referring to FIG. 15 , the optical coupler may opticallyconnect one or more optical components (e.g., optical fiber 1502) to oneor more PICs 1504. PICs may comprise optical-to-electrical conversionelements to convert optical signals to electrical signals, and/orelectrical signals to optical signals. PIC 1504 may be additionally bein electrical communication with one or more electrical components(e.g., ASIC-1 1554A, and ASIC-2 1554B). Accordingly, interposer spacersubstrate 1518 may comprise one or more electrical through-hole vias1556. Electrical through-hole vias 1556 may electrically connectedcomponents electrically contacted thereto. For example, PIC 1504 maycomprise any number of features for electrical connection, for example,solder bumps and/or micro-bumps 1558, etc. Similarly, ASIC-1 1554Aand/or ASIC-2 1554B may comprise any number of features for electricalconnection, for example, solder bumps and/or micro-bumps 1558. Thefeatures for electrical connection may be in electrical contact with thecorresponding component (e.g., PIC 1504, ASIC-1 1554A, ASIC-2 1554B).The features for electrical connection may additionally be electricallyconnected to through-hole vias 1556 to effect electrical connectionbetween components (e.g., PIC 1504 and AISIC-1 1554A). In addition tofacilitating electrical connection, interposer spacer substrate 1518 maycomprise features to facilitate optical connection. Such features maycomprise optical features as described herein, for example, one or morecurved mirrors, one or more optical mirrors, features of photonic bumps(as described below), materials and/or layers to facilitate opticalconnection.

As described, the optical couplers herein may couple an optical signalbetween an optical source and an optical drain. According to aspects,the optical source components or the optical drain components may be aPIC (which may further be variously optically and/or electricallyconnected to additional components). Accordingly, aspects of the presentdisclosure relate to optical component and/or elements (e.g., PIC I/Ointerfaces) for interfacing optical signals with PICs. Often, PICs mayhave one or more PIC I/O waveguides. PIC I/O waveguides may be theelement through which the PIC optically communicates with othercomponents and may receive incoming optical signals and may transmitoutgoing optical signals. As described, present solutions to opticalcoupling with a PIC may comprise side coupling to the PIC (e.g., wherethe optical source/drain component is placed in the same plane as thePIC). Such side coupling may be associated with burdensome assemblytolerances and may not result in high yield with fiber assembly.Accordingly, the present disclosure discloses systems, methods, andapparatuses that, amongst other advantages, removes the opticalcomponent (e.g., optical source/drain) (e.g., optical fiber, laser) fromthe plane of the PIC (e.g., optical source/drain) with relaxed assemblytolerances. Accordingly, one or more elements and/or components may beused to direct (e.g., reflect, propagate, redirect) the optical signalinto/out of the plane of the PIC (and/or PIC I/O waveguide).Additionally, optical coupling is often associated with coupling of oneor more optical components being associated with (may be referred toherein as “having”) different mode diameters (e.g., beam waist). Forexample, it is often desirable to optically couple a single mode fiber(SMF) and/or a laser to a PIC. SMFs may have example core diameters inthe range of about 8 micrometer to about 10.5 micrometer. Accordingly,the mode diameter of an optical signal for these typical SMFs may be ina similar range (note, mode diameter may deviate from (e.g., be largerthan) SMF core diameter). However, PIC I/O waveguides (to which it maydesirable to optically connect a SMF) may be differently sized. Forexample, PIC I/O waveguides may be in the example range of 3-5 micron.Therefore, it may be desirable to substantially match the modes (e.g.,via expansion elements, contraction elements, etc.) to efficientlyconnect optical components (e.g., lasers, optical fibers) requiringdifferent mode sizes. Accordingly, one or more aspects of the presentdisclosure relate to mode matching for effective and efficient opticalcoupling between optical components having, requiring, and/or beingassociated with different mode diameters. Note, while the example SMFhaving an example core diameter of about 8-10 micron, and example PICshaving example PIC I/O waveguides of an example range of about 3-5micron, have been described, such description is intended for purposesof illustration only. Accordingly, aspects of the present disclosurerelate to optically coupling any components requiring and/or beingassociated with different mode diameters (or the same mode diameters).Accordingly, aspects of the present disclosure relate to PIC I/Ointerfacing and/or PIC I/O interface elements that may perform one orboth mode matching and/or signal direction. Some or all of such PIC I/Ointerfacing may be referred to herein and Photonic Bumps.

FIG. 16A depicts an example turning curved mirror PIC I/O interface(also referred to as a photonic bump and/or a TCM photonic bump)according to one or more aspects of the present disclosure. Referring toFIG. 15 , turning curved mirror (TCM) 1660 may allow efficient wide-bandsurface optical coupling. Further, TCM 1660 may allow for modeconversion (e.g., mode matching) of an optical signal to facilitateefficient coupling of optical components having different mode diameters(e.g., different mode size requirements) (e.g., PIC (e.g., with a PICI/O waveguide) to an optical fiber having a different mode sizerequirement). Additionally, according to aspects, such mode conversionmay be substantially accomplished by the TCM 1660. Further still, theTCM may allow for further alignment relaxation when optically connectingoptical components (e.g., PIC to optical fiber). Additionally, the TCM1660 may be fabricated with high volume semiconductor manufacturing(e.g., SOI, CMOS, grayscale lithography, nanoimprint lithography, etc.).The TCM 1660 may additionally enable improved wafer level testing. Forexample, in side-coupling optical solutions, the wafer may requiredicing prior to full testing. Whereas, with optical couplers comprisinga TCM 1660 (e.g., enabling surface coupling), the full wafer may betested prior to dicing and further packaging with other components. As aresult, in addition the other advantages described herein, manufacturingyield may be significantly improved. A layer of dielectric material, forexample, metal (e.g., aluminum, chromium, gold, silver, etc.) may bedeposited (e.g., coated on) the TCM 1660. Alternatively, TCM 1660 may befabricated variously and may be incorporated with PICs and/or substratesvariously. Additionally, the TCM 1660 may interface with opticalcouplers of the present disclosure to allow for the optical coupling ofoptical components (e.g., PIC to optical fiber).

Referring to FIG. 16A, PIC 1604 may comprise PIC I/O waveguide 1662 forthe input and output of optical signals to/from the PIC 1604. The TCMmay be placed and arranged such that the beams entering and exiting thePIC I/O waveguide may be interfaced with the TCM 1660. The TCM 1660 maymanipulate (e.g., expand and/or contract) the optical signal 1616 anddirect and reflect the optical signal 1616 to additional opticalelements. As an example, assuming the PIC 1604 acts as the opticalsource component, an optical signal 1616 may exit the PIC I/O waveguide1662 as a divergent beam propagating toward the TCM 1660. The opticalsignal may be incident upon the TCM 1660. The TCM 1660 may redirect thebeam (e.g., turn the beam) and reflect the beam toward an additionaloptical element (e.g., the optical coupler curved mirror 1612). The TCM1660 may, in addition to redirecting the beam (e.g., optical signal),perform beam manipulation. Such beam manipulation may expand or contractthe beam to match the mode of the optical component to which the PIC1604 is coupled. For example, if the PIC 1604 is coupled to an opticalfiber 1602 (e.g., a SMF) having a larger mode diameter than the PIC I/Owaveguide 1662, the TCM 1660 may expand the beam to match the modediameter of the optical fiber 1602. Thus, it can be appreciated that theTCM 1660 may achieve beam direction/redirection, beam manipulation(e.g., mode matching), and may allow for wideband coupling (as it is areflective element).

While the above is described in terms of the PIC 1604 acting as thesource component, the same may apply in reverse, where the PIC 1604 mayacts as the optical drain component. If the PIC 1604 acts as the draincomponent, the TCM 1660 may receive the optical signal 1616 (e.g., fromthe optical coupler) that may originate from an optical source (e.g.,optical fiber 1602, laser, etc.) that may have a larger mode diameter.The TCM 1660 may then: 1) direct the optical signal toward the PIC I/Owaveguide 1662; and 2) accomplish mode matching by reducing the modediameter of the optical signal to match the mode diameter requirementsof the PIC I/O waveguide 1662. While the above is described with respectto a PIC 1604 having a PIC I/O waveguide 1662 with smaller mode diameterrequirements than the optically connected optical component, the presentmay similarly operate where the PIC I/O waveguide 1662 has larger modefield requirements than the optically connected optical component.

According to aspects, the TCM 1660 may be incorporated in a photonicbump 1664. The photonic bump 1664 may further comprise a photonic bumpcurved mirror (PB curved mirror) 1610. The PB curved mirror 1610 mayinterface the optical signal 1616 between multiple optical elementsand/or optical components (e.g., an optical coupler curved mirror, andoptical coupler tilted mirror, and optical fiber, etc.). If implementedwith an optical coupler, PB curved mirror 1612 may interface an opticalsignal 1616 with the curved mirror of the optical coupler 1612 (e.g.,curved mirror in the PhotonicPlug layer of the optical coupler), and aturning mirror of the optical coupler 1600 (e.g., turning mirror in thePhotonicPlug layer of the optical coupler). The PB curved mirror 1610may interface an optical signal variously.

The photonic bump 1664 may be fabricated variously. For example, thephotonic bump 1664 may be fabricated on a PIC. Alternatively, thephotonic bump 1664 may be fabricated on a substrate (e.g., a PICsubstrate 1622, e.g., SiPh substrate). The substrate may be the samesubstrate or a different substrate from the substrate in which the PICis fabricated. The photonic bump 1664 may be fabricated around the timethe PIC is fabricated. Alternatively, the photonic bump 1664 may beadded to a substrate comprising a PIC at a later time. For example, acavity 1666 may be formed in PIC substrate 1622. The TCM 1660 may befabricated in the cavity 1666 using, for example, wafer level processes.Additionally or alternatively, the TCM 1660 may be variously added tothe PIC substrate 1622, via, for example, additive manufacturing,deposition manufacturing. Additionally or alternatively, the TCM 1660may be variously placed in the cavity 1666 and variously attached to thePIC substrate 122. The PB curved mirror 1610 may similarly be added toPIC substrate 122 using, for example, wafer level manufacturingprocesses and/or other processes of mirror fabrication described herein.The photonic bump 1664 may be fabricated using any one of numerousmethods identifier herein (e.g., CMOS, NIL, greyscale lithography,etc.). For example, alternatively, the TCM 1660 and/or the photonic bump1664 may be formed on the spacer 1618. The spacer 1618 comprising theTCM 1660 and/or the photonic bump 1664, may be added (e.g., assembledwith, attached, etc.) to the PIC substrate 1622. As described herein,such assembly may use, for example, alignment marks on one or more ofthe assembled substrates (e.g., the spacer 1618 and/or the PIC substrate1622) to facilitate accurate assembly of the substrates and opticalelements. The PIC substrate 1622 and/or the spacer substrate 1618 mayfurther comprise physical alignment features as described herein.

The photonic bump 1664 may be used in conjunction with an opticalcoupler (e.g., PhotonicPlug layer and spacer layer) to optically coupleoptical components (e.g., PIC to optical fiber). Accordingly, if in usein conjunction with an optical coupler, the beam may propagate throughthe optical coupler and photonic bump 1664. The optical signal 1616 mayenter/exit the optical coupler at the optical component (e.g., opticalfiber 1602). A first turning mirror 1620 may interface the opticalsignal between the optical component (e.g., optical fiber 1602, laser)and the PB curved mirror 1610. The PB curved mirror 1610 may interfacethe optical signal 1616 between the optical coupler curved mirror 1612and the first turning mirror 1620. Depending on direction of opticalsignal propagation, the PB curved mirror 1610 may either substantiallycollimate the optical signal 1616 (e.g., toward the optical couplercurved mirror 1612) or substantially focus the optical signal 1616(e.g., toward the first turning mirror 1620). The optical couplerturning mirror 1612 may interface the optical signal between the PBcurved mirror 1610 and the TCM 1660. The TCM 1660 may interface theoptical signal between the optical coupler curved mirror 1612 and thePIC I/O waveguide 1662. The TCM 1660 may, in addition to interfacing theoptical signal as described, provide mode matching beam manipulation totransform the optical signal 1616 (e.g., optical beam) from a first modediameter to a second mode diameter (e.g., expand or contrast the modediameter of the optical signal).

FIG. 16B depicts a plurality of example TCM photonic bumps on a PICsubstrate 1622. Referring to FIG. 16B, PIC substrate 1622 may compriseone or more PICs 1604. The PIC substrate may be, for example a SiPhsubstrate. The one or more PICs 1604 may comprise one or more PIC I/Owaveguides 1622 (FIG. 16B depicts an example five PIC I/O waveguides1662A-1662E (generally PIC I/O waveguide 1622)). In order to facilitateoptical connection of the PIC I/O waveguides 1662 to other opticalcomponents (e.g., optical fibers, lasers, etc.) the PIC substrate maycomprise a TCM photonic bump for some of or each PIC I/O waveguide. EachTCM photonic bump may comprise a TCM 1660 (FIG. 6B depicts five exampleTCMs 1660A-1660E (generally TCM 1660)). Each TCM 1660 may be orientedsuch that it may interface an optical signal with its corresponding PICI/O waveguide 1662 (e.g., an optical signal from the corresponding PICI/O waveguide 1662 may be incident upon the TCM 1660, and an opticalsignal from the TCM may enter the PIC I/O waveguide 1662). Each TCM 1660may redirect an optical signal that is incident thereupon, and may alterthe optical signal (e.g., alter and/or transform the mode diameter ofthe optical signal) to match a desired mode diameter. Additionally, eachTCM photonic bump may further comprise a PB curved mirror 1610 (FIG. 6Bdepicts five example PB curved mirrors 1610A-1610E (generally PB curvedmirror 1610)).

The TCM photonic bumps of FIG. 16B may, for example, facilitate opticalconnection of the PIC I/O waveguides to additional optical components(e.g., optical fibers, lasers, other PICs) via for example, one or moreoptical couplers of the present disclosure. For example, an opticalfiber corresponding to each PIC I/O waveguide may be connected to anoptical coupler (e.g., at the PhotonicPlug layer). The optical couplermay comprise a first turning mirror and an optical coupler curved mirrorfor each connected optical fiber. The optical coupler may be alignedwith and installed to PIC substrate 1622 such that each PIC I/Owaveguide is optically coupled to each optical fiber via eachcorresponding TCM photonic bump and optical coupler curved mirror andfirst turning mirror. Example TCM photonic bump is illustrated in FIG.16A as connecting a PIC to an optical fiber, and example TCM photonicbump is illustrated as interfacing one or more PICs. It should beappreciated that TCM photonic bumps may be used to optically connect anycombination of optical components e.g., optical chips (e.g., PICs),optical fibers (e.g., SMF, polarization maintaining fibers (PM fibers),few mode fibers, multi-mode fibers), lasers, etc.).

FIGS. 16C and 16D depict example TCMs executing optical signalredirection and mode conversion according to one or more aspects of thepresent disclosure. Referring to FIG. 16C, optical signal 1616A may beincident upon the TCM 1660. Optical signal 1616A may comprise a gaussianbeam. The TCM 1660 may deflect the optical signal 1616 (e.g., reflectthe optical signal 1616A in a different direction than the direction atwhich it approached TCM 1660). Additionally, as depicted in FIG. 16C,the signal may have one mode diameter before the TCM 1660 and adifferent mode diameter after the TCM 1660. FIG. 16D depicts a TCM 1660substantially as described with respect to 16C reflecting and modetransforming a non-gaussian optical beam 1616B.

FIG. 16A depicts an example TCM photonic bump 1664 on the PIC 1604and/or the PIC substrate 1622. Additionally or alternatively, the TCM1660 and/or the TCM photonic bump may be fabricated as a part of thespacer. FIG. 16E depicts an example TCM photonic bump 1664 according toone or more aspects of the present disclosure. Referring to FIG. 16E,the TCM 1660 may be fabricated as a part of the spacer 1618.Additionally or alternatively, the TCM curved mirror 1610 may befabricated as a part of the spacer 1618. For example, the shape of theTCM 1660 and/or the TCM curved mirror 1610 may be fabricated in thespacer 1618. One or layers of dielectric may be deposited on the shapesof the TCM 1660 and/or the TCM curved mirror 1610. Alignment marksand/or mechanical alignment features may be included in either or bothof the spacer 1618 and/or the PIC 1604. The spacer 1618 may assembledwith the PIC 1604 (and additional components (e.g., a PhotonicPlug)) toeffectuate an optical coupler using a TCM photonic bump 1664 asdescribed herein.

FIGS. 16A-16E show example TCM photonic bumps, other photonic bumps, forexample, to facilitate optical connection of optical components arecontemplated herein. FIG. 17 depicts an example grating coupler photonicbump 1764 according to the present disclosure. Referring to FIG. 17 ,the grating coupler photonic bump 1764 may be used to couple an opticalsignal 1716 between optical source and optical drain components (e.g.,additional PIC I/O interface elements 1728 (e.g., PIC I/O waveguide andoptical fiber 1702). The grating coupler photonic bump 1764 may comprisea grating coupler 1755. The grating coupler 1755 may be used to changethe direction of an optical signal 1716. For example, the gratingcoupler 1755 may receive and optical signal from the PIC 1704 (e.g.,additional PIC I/O interface elements 1728). The grating coupler 1755may redirect the optical signal 1718 from the plane of the PIC 1704 atan angle to the plane of the PIC 1704 (e.g., in an example configurationat an angle in an example range of from 8° to 12°). Alternatively, inthe reverse direction, the grating coupler 1755 may receive an opticalsignal at an angle to the PIC I/O waveguide 1762 and from an opticalcomponent (e.g., the second curved mirror 1712). The grating coupler mayreceive the optical signal 1716 at an angle to the PIC I/O waveguide1762 and may redirect the optical signal 1716 into the plane of the PICI/O waveguide 1762. Accordingly, the grating coupler 1755 may couple anoptical signal with the PIC I/O waveguide 1755. The grating coupler 1755may additionally comprise a mode converter that may convert the modesize of the optical signal 1716.

The grating coupler photonic bump 1764 may further comprise a GC curvedmirror 1710. The GC curved mirror 1710 may comprise a curved mirrorsubstantially as described herein (for example as described in relationto curved mirrors of FIG. 1 ). The GC curved mirror 1710 may facilitateoptical connection between an optical source component and optical draincomponent, as would be understood from the present disclosure. Thegrating coupler 1755 and/or the grating coupler photonic bump 1764 maybe fabricated on the PIC substrate 1722 using one or more fabricationmethods described herein (e.g., NIL, CMOS, etc.). Additionally oralternatively, the grating coupler 1755 and/or the grating couplerphotonic bump 1764 may be fabricated as a part of the spacer 1718. Thespacer may be assembled with the PIC 1704 or other components. Thespacer and/or the PIC may comprise alignment features to assist properassembly alignment of the substrates and the optical elements.Additionally or alternatively, the spacer and/or the PIC may comprisemechanical alignment features to assist proper assembly alignment of thesubstrates.

FIG. 18A depicts an example tapered waveguide photonic bump 1870according to one or more aspects of the present disclosure. The taperedwaveguide photonic bump 1870 may facilitate wideband surface opticalcoupling between optical components (e.g., PIC, optical fiber, laser,etc.). The tapered waveguide photonic bump 1870 may provide suchconnection while assisting with signal coupling efficiency,mode-conversion, wide-band surface coupling, wafer level testing, lowsignal losses, thermal stability, and relaxed alignment between the PICand the connected optical component. The tapered waveguide photonic bump1870 may perform one or more of numerous functions. For example, thetapered waveguide photonic bump 1870 may transform (e.g., expand,contract etc.) the beam diameter of the optical signal being coupled(e.g., mode-conversion of the optical signal). Additionally oralternatively, the tapered waveguide photonic bump 1870 may turn ordirect the signal being coupled. Additionally or alternatively, thetapered waveguide photonic bump 1870 may interface with an opticalcoupler 1800 to facilitate optical connection of optical components.Additional functions of the tapered waveguide photonic bump may beappreciated from the present disclosure.

Referring to FIG. 18A, optical coupler 1800 may be used to opticallycoupler an optical fiber 1802 to a PIC 1804. PIC 1804 may have a PIC I/Owaveguide 1862 to accept/receive input optical signals and emit/transmitoutput optical signals. Thus, it may be desirous to efficientlyinterface optical signals with the PIC I/O waveguide 1862. PIC I/Owaveguide 1862 may be inverse tapered (see FIGS. 18A-18C) to facilitatethe expansion of optical signals and to facilitate the efficientcoupling of optical signals to further elements (e.g., tapered waveguide1844, optical fiber). Additionally, such PIC I/O waveguides 1862 may beof varying cross-sectional size. Such cross-sectional size may bedifferent (e.g., smaller) than the mode diameter of the coupled opticalfiber 1802. Accordingly, it may be advantageous to transform/convert thebeam diameter of the optical signal 1816 to assist efficient coupling ofthe PIC I/O waveguide 1862 with the optical fiber 1802 that may have amode diameter of a different size. Accordingly, tapered waveguide 1844may be implemented to assist with the efficient coupling of the opticalfiber 1802 to the PIC 1804. The tapered waveguide 1844 may be tapered ina first dimension. FIG. 18B depicts a cross-section of the exampletapered waveguide photonic bump in a first dimension according to one ormore aspects of the present disclosure. Referring to FIG. 18B, thetapered waveguide may be tapered from a larger first height h1 to asmaller second height h2. The tapered waveguide may comprise threeportions, a first height portion 1848, a tapered portion 1868, and asecond height portion 1838. Each portion may be of varying lengths. Thetapered waveguide 1844 may be adiabatically tapered from first height h1to second height h2. A cross-section of the tapered portion 1868 in afirst dimension may form a first trapezoidal shape. The firsttrapezoidal shaped cross-section may form a substantially righttrapezoidal shape or a substantially isosceles trapezoidal shape.According to aspects, the tapered waveguide 1868 may be fabricated andconfigured to expand the beam to a diameter that is substantiallysimilar to the mode diameter of an optical fiber to which the PIC isbeing coupled. Thus, according to aspects, the first height h1 may besubstantially similar to the size of the mode diameter of the opticalfiber to which the PIC is being coupled. The second height portion maybe configured to efficiently couple the tapered waveguide 1844 to a PICI/O waveguide 1862. For example, the second height portion may expandthe beam from, a PIC I/O waveguide mode size (e.g., less than onemicron) to the second height portion mode size (e.g., 3-5 microns).

According to aspects, the tapered waveguide 1844 may be fabricated on anoxide layer 1840. The tapered waveguide 1844 may be fabricated of apolymer (e.g., polyimide) or nitrides such as silicon nitride, siliconoxynitride, or any material with a suitable refractive index. Suchrefractive index may be suitably low allowing the tapered waveguide, atthe second height portion 1838, to readily expand the beam after it isreceived from the PIC I/O waveguide 1862. Thus, according to aspects,the index of refraction of the tapered waveguide 1844 or a portion ofthe tapered waveguide 1844, (e.g., the second height portion 1838) maybe lower than the index of refraction of the PIC I/O waveguide 1862 andthe underlying oxide layer 1840.

FIG. 18C depicts a cross-section of the example tapered waveguidephotonic bump in a second dimension, substantially perpendicular to thefirst dimension of FIG. 18B, according to one or more aspects of thepresent disclosure. Referring to FIG. 18C, the tapered portion of thetapered waveguide 1844 may be additionally tapered in a second dimensionsubstantially perpendicular to the first dimension (as depicted in FIG.18B). Like the first cross-section in the first dimension, the taperedwaveguide 1844 may comprise three portions, a first height portion 1834,a tapered portion 1868, and a second height portion 1838. The taperedportion 1868 may taper the waveguide from the larger first heightportion 1848 to the smaller second height portion 1838. The waveguidemay be adiabatically tapered from the first height h1 to the secondheight h2. The taper in the second dimension may form a secondtrapezoidal cross-section. The second trapezoidal cross section may forma substantially isosceles trapezoidal shape or may form a substantiallyright trapezoidal shape. According to aspects, the tapered waveguide maybe fabricated and configured to expand the beam to a diameter that issubstantially similar to the mode diameter of an optical component(e.g., optical fiber) to which the PIC may be coupled. Thus, accordingto aspects, the first height, h1, may be substantially similar to thesize of the mode diameter of the optical component (e.g., optical fiber)to which the PIC is coupled. The second height may be similar to thatwhich is described above in relation to the first cross-section in thefirst dimension.

Referring to FIG. 18A, The tapered waveguide photonic bump 1870 may beconfigured to interface the optical signal with one or more aspects ofthe optical couplers according to the present disclosure. Accordingly,tapered waveguide photonic bump 1870 may comprise one or more mirrors(or lenses) to facilitate such optical interfacing. Referring to FIG.18A, the tapered waveguide photonic bump 1870 may comprise a taperedwaveguide photonic bump turning mirror 1850 and a tapered waveguidephotonic bump curved mirror 1810. The tapered waveguide photonic bumpturning mirror 1850 may be substantially flat and may be configured anddisposed at a predefined angle with respect to the tapered waveguide1844 and/or the underlying substrate. The tapered waveguide photonicbump turning mirror 1850 may interface the optical signal 1816 with thetapered waveguide 1844. Additionally, the tapered waveguide photonicbump turning mirror 1850 may interface the optical signal 1816 with oneor more additional optical elements (e.g., coupler curved mirror 1812)to facilitate the optical connection of PIC 1804 and a further opticalcomponent (e.g., optical fiber 1802). If the PIC 1804 acts as theoptical source component, the light beam 1816 may enter the secondheight portion of the tapered waveguide from the PIC I/O waveguide 1862.The first height portion may expand the beam from the PIC I/O waveguidemode to the first height portion mode. The beam may continue to thetapered portion of the tapered waveguide. The tapered portion mayfurther expand the beam adiabatically. According to aspects, the taperedportion may expand the signal beam to substantially match the size ofthe mode diameter of the optical fiber 1802 to which the PIC 1804 isbeing coupled. According to further aspects, the tapered portion mayexpand the beam to various sizes that may or may not match the size ofthe mode diameter of the optical fiber 1802 to which the PIC 1804 isbeing coupled. The beam may continue to the first height portion of thetapered waveguide and from the first height portion to the taperedwaveguide photonic bump turning mirror 1850. The tapered waveguidephotonic bump turning mirror 1850 may receive the beam from the firstheight portion of the tapered waveguide 1844 and may reflect and directthe signal to subsequent optical elements (e.g., coupler curved mirror1812). The tapered waveguide photonic bump turning mirror 1850 may bedisposed in the tapered waveguide photonic bump at a predefined angle toredirect the optical signal 1816 to subsequent optical elements (e.g.,coupler curved mirror 1812).

If the PIC 1804 acts as the optical drain component, the taperedwaveguide photonic bump turning mirror 1850 may receive the opticalsignal 1816 from additional optical components (e.g., coupler curvedmirror 1812) and may reflect and direct the optical signal 1816 into thefirst height portion of the tapered waveguide 1844. According toaspects, the tapered waveguide photonic bump turning mirror 1850 may bedisposed at a predefined angle to direct the received optical signalinto the first portion of the tapered waveguide 1844. The first heightportion may receive the optical signal 1816 from tapered waveguidephotonic bump turning mirror 1850. The optical signal 1816 may continueto the tapered portion of the tapered waveguide 1844. The taperedportion may adiabatically contract the optical signal mode to the modeof the second height portion. The optical signal 1816 may continue tothe second height portion where the optical signal may be coupled withPIC I/O waveguide 1862.

According to aspects, the tapered waveguide photonic bump 1870 mayfurther comprise a tapered waveguide photonic bump curved mirror 1810.The tapered waveguide photonic bump curved mirror 1810 may perform thefunctions substantially as described with relation to the first curvedmirror elsewhere herein. Accordingly, the tapered waveguide photonicbump curved mirror 1810 may perform optical signal manipulation and/ortransformation and may interface the optical signal 1816 with theadditional optical components (e.g., turning mirror (e.g., couplerturning mirror 1820), curved mirror (e.g., coupler curved mirror 1812),and optical fiber 1802). Thus, the tapered waveguide photonic bump 1870may operate in tandem with an optical coupler 1800 to optically couplean optical source component to an optical drain component. According toaspects, a PIC may act as and/or be configured similarly to a sourcecomponent. Accordingly, the optical signal 1816 may propagate from thePIC I/O waveguide 1862, to the tapered waveguide 1844. The taperedwaveguide 1844 may manipulate the optical signal as described herein.The manipulated optical signal may be received and reflected by thetapered waveguide photonic bump turning mirror 1850 toward an opticalcoupler curved mirror 1812 (e.g., in the PhotonicPlug layer of theoptical coupler). The optical coupler curved mirror 1812 maysubstantially collimate the optical signal and reflect the substantiallycollimated optical signal toward the tapered waveguide photonic bumpcurved mirror 1810. The tapered waveguide photonic bump curved mirror1810 may receive the substantially collimated optical signal 1816 andsubstantially focus the optical signal 1816 toward an additional opticalelement or component (e.g., optical coupler tilted mirror 1820 oroptical fiber 1802).

According to aspects, the PIC 1804 may act as and/or be configuredsimilarly to the optical drain component. Accordingly, the opticalsignal 1816 may propagate substantially in the reverse of that which isdescribed immediately above. According to such aspects, the taperedwaveguide photonic bump curved mirror 1810 may receive a substantiallydivergent optical signal from an optical component or optical element(e.g., optical fiber 1802 or optical coupler turning mirror 1820). Thetapered waveguide photonic bump curved mirror 1810 may substantiallycollimate and reflect the optical signal 1816 toward the optical couplercurved mirror 1812. The optical coupler curved mirror 1812 may receivethe substantially collimated optical signal 1816, may substantiallyfocus the optical signal 1816 and may reflect the substantially focusedoptical signal 1816 toward the tapered waveguide photonic bump turningmirror 1850. The tapered waveguide photonic bump turning mirror 1850 mayreceive the focusing optical signal 1816 and may reflect the focusingoptical signal 1816 into the tapered waveguide 1844. The taperedwaveguide may manipulate (e.g., contract) the optical signal 1816, andcouple the optical signal 1816 with the PIC I/O waveguide 1862.

Further aspects of the present disclosure relate to opto-electricalpackaging and optical and electrical connection within a system levelarchitecture. FIG. 19 depicts an example electro-optical packageaccording to one or more aspects of the present disclosure. Referring toFIG. 19 , the package may comprise one or more chiplets 1905. Chiplets1905 may comprise, for example, optical engines and/or PICs (e.g., SiPhchip), additional package substrates, one or more interposers and/or oneor more electrical components or chips (e.g., digital signal processor(DSP), transimpedance amplifier (TIA), and/or driver). The chiplets 1905may be placed within close proximity (e.g., within a few millimeters orless distance) to an EIC 1970, for example a processor (e.g., GPU, DPU,CPU, etc.) and/or a switching unit. The proximity of the chiplets 1905and the EIC 1970 may allow for high speed connectivity of the twoelements. The chiplets 1905 and the EIC 1970 may be placed on, andvariously packaged with, package substrate 1978, for example, a printedcircuit board (PCB), a multi-chip module (MCM) substrate, an organicsubstrate, etc. The package substrate 1978 may provide electricalconnectivity between the chiplets 1905 and the EIC 1970 as described inmore detail herein. Chiplets 1905 may comprise components to convertand/or translate optical signals into electrical signals. Additionally,chiplets 1905 may comprise components to convert and/or translateelectrical signals into optical signals. While FIG. 19 depicts 16chiplets 1905 in communication with a single EIC 1970 it should beunderstood that the same principles may be applied to connect any numberof chiplets 1905 (e.g., 1, 100, 5000, etc.) to any number of EICs 1970.Additionally, any number of electrical components may be connected tothe chiplet(s) 1905 and/or the EIC(s) 1970 variously. For example, EIC1970 may be additionally electrically connected to one or more highbandwidth memory (HBM) units on the same package substrate 1978. Opticalcouplers 1900 of the present disclosure (for example, one or more of theoptical couplers described in relation to FIGS. 1-5C) may be used tooptically connect optical components to the chiplets 1905.

Additional components may be used in such an opto-electrical packagingand connection system. FIG. 20A depicts an example electro-opticalsystem according to one or more aspects of the present disclosure.Referring to FIG. 20A, the system may comprise a package substrate 2078(e.g., PCB, MCM, organic substrate, interposer, etc.). EIC 2070 (e.g.,CPU, GPU, ASIC, etc.) may be electrically connected to the packagesubstrate 2078. Memory unit 2092, (e.g., high-bandwidth memory (HBM)unit) may additionally be electrically packaged with and/or on packagesubstrate 2078. One or more additional computing components and/orcircuits may be placed on the package substrate or alternativelyconnected to the package substrate. PIC 2004 may be packaged with thepackage substrate 2078 and may be electrically connected to packagesubstrate 2078. PIC 2004 may be placed in proximity to one or more ofthe computing components (e.g., processor unit, memory unit, EIC 2070,etc.). Package substrate 2078 may electrically connect PIC 2004 to oneor more of the co-packaged computing components (e.g., chips, EIC).

Electrical and optical components may be packaged and connected to eachother variously. Electrical and optical interconnection between EICs maybe achieved variously within an electro-optical package. Referring toFIG. 20A, PIC 2004 and EIC 2070 (e.g., ASIC 1554) may be placed onpackage substrate. PIC 2004 and EIC 2070 may be electrically connectedto package substrate (e.g., with solder balls, reflow soldered, socketconnection, etc.). Additionally or alternatively, PIC 2004 (e.g.,optical engine) may be placed in proximity to EIC 2070. PIC 2004 and EIC2070 may be additionally electrically connected to each other via wirebonding. Optical coupler 2000 (for example, optical coupler as describedherein with respect to FIGS. 1-18 ) may be connected to PIC 2004. Thoughnot fully depicted for clarity of illustration in FIG. 20A, it should beunderstood that optical coupler 2000 may comprise first optical elements2051 (e.g., first turning mirror 120 and/or second curved mirror 112).Additionally, corresponding second optical elements 2053 (e.g., firstcurved mirror 110, TCM photonic bump 1664, tapered waveguide photonicbump 1870, grating coupler photonic bump 1764, and/or one or more PICI/O interface elements (e.g., PIC I/O waveguide 1662) may be integratedwith PIC 2004. Additionally, optical coupler 2000 may comprise one ormore of PhotonicPlug layer (e.g. PhotonicPlug layer 106) and spacerlayer (e.g., spacer layer 108) to facilitate optical coupling of one ormore optical components (e.g., optical fiber 2002, laser, PIC, and/orchiplet, etc.) to the PIC 2004.

FIG. 20B depicts an example electro-optical package according to one ormore aspects of the present disclosure. Referring to FIG. 20B, PIC 2004may be placed on package substrate. PIC 2004 may be electricallyconnected to package substrate via wire bonding. Additionally oralternatively, PIC 2004 may be electrically connected to packagesubstrate variously, (e.g., surface reflow soldered, socket connection,solder bumps, etc.). PIC 2004 (e.g., optical engine) may host EIC 2070.EIC 2070 may be placed on the PIC 2004. EIC 2070 may be electricallyconnected to the PIC 2004. The EIC 2070 may be electrically connected tothe PIC 2004 variously. For example, the EIC 2070 may be electricallyconnected, for example, using a flip-chip technique, solder bumps,reflow, and/or sockets. Alternatively, the EIC 2070 may be electricallyconnected to the PIC 2004 via wire bonding. The EIC 2070 may beadditionally or alternatively electrically connected to the packagesubstrate 2078 and/or one or more additional EICs. For example, the EICmay be wire bond connected to the package substrate 2078 and/or one ormore additional EICs. Optical coupler 2000 (for example, optical coupleras described herein with respect to FIGS. 1-18 ) may be connected to PIC2004. Though not fully depicted for clarity of illustration in FIG. 20B,it should be understood that optical coupler 2000 may comprise firstoptical elements 2051 (e.g., first turning mirror 120 and/or secondcurved mirror 112). Additionally, corresponding second optical elements2053 (e.g., first curved mirror 110, TCM photonic bump 1664, taperedwaveguide photonic bump 1870, grating coupler photonic bump 1764, and/orone or more PIC I/O interface elements (e.g., PIC I/O waveguide 1662)may be integrated with PIC 2004. Additionally, optical coupler 2000 maycomprise one or more of PhotonicPlug layer (e.g. PhotonicPlug layer 106)and spacer layer (e.g., spacer layer 108) to facilitate optical couplingof one or more optical components (e.g., optical fiber 2002, laser, PIC,and/or chiplet, etc.) to the PIC 2004.

FIG. 21 depicts an example electro-optical package according to one ormore aspects of the present disclosure. Referring to FIG. 21 , PIC 2104may be placed on package substrate 2178 (e.g., organic substrate, MCMsubstrate). PIC 2104 may be electrically connected to package substrate2178 via, for example, solder bumps (e.g., micro-bumps and solderreflow). Additionally, EIC 2170-1 may be packaged with package substrate2178. EIC 2170 may similarly be electrically connected to packagesubstrate via solder bumps. One or more additional EICs may be similarlyelectrically connected to the package substrate 2178. The packagesubstrate 2178 may be electrically connected to another substrate, e.g.,a board 2198 (e.g., PCB) via, for example a ball grid array (BGA).

Referring to FIG. 21 , PIC 2104 may be packaged with package substrate2178. PIC 2104 may be electrically connected to package substrate 2178via solder bumps (e.g., micro-bumps and solder reflow). As described,PIC 2104 may host one or more EICs. EICs may be placed on, andelectrically connected to PIC 2104. EIC 2170-2 may be electricallyconnected to PIC 2104 via, for example, solder bumps (e.g.,micro-bumps). One or more additional EICs may be similarly packaged withPIC 2104. Additionally or alternatively, one or more additional EICs maybe placed on and electrically connected to package substrate. Packagesubstrate 2178 may be further electrically connected to anotherpackage/substrate. For example, package substrate may be connected toboard 2198 via, for example BGA (and/or wire bonding). Optical coupler2100 (for example, optical coupler as described herein with respect toFIGS. 1-18 ) may be connected to PIC 2104. Though not fully depicted forclarity of depiction and description in FIG. 21 , it should beunderstood that optical coupler 2100 may comprise first optical elements2151 (e.g., first turning mirror 120 and/or second curved mirror 112).Additionally, corresponding second optical elements 2153 (e.g., firstcurved mirror 110, TCM photonic bump 1664, tapered waveguide photonicbump 1870, grating coupler photonic bump 1764, and/or one or more PICI/O interface elements (e.g., PIC I/O waveguide 1662) may be integratedwith PIC 2004. Additionally, optical coupler 2100 may comprise one ormore of PhotonicPlug layer (e.g. PhotonicPlug layer 106) and spacerlayer (e.g., spacer layer 108) to facilitate optical coupling of one ormore optical components (e.g., optical fiber 2102, laser, PIC, and/orchiplet, etc.) to the PIC 2104.

According to aspects of the present disclosure, optical couplers may beused and integrated with 2.5D and 3D packaging. In 2.5D two or moreactive chips (e.g., EICs) may be placed laterally on an interposer. Theinterposer may be, for example, silicon, and may contain circuitry tointerconnect the two or more chips disposed thereon, and circuitry toconnect the two or more chips to additional components. The interposermay, according to aspects, comprise through silicon vias (TSV) as willbe described in more detail herein. 3D packaging active chips integratedby die stacking. FIG. 22 depicts an example optical coupler integratedwith 2.5D and 3D electronic packaging. Referring to FIG. 22 , PIC 2204may be placed on and electrically connected to interposer 2294. One ormore EICs 2204 (e.g., TIA, drivers, etc.) may be laterally disposed on,and electrically connected to, the interposer 2294. The interposer 2294may comprise circuitry to interconnect the PIC 2204 and the EIC 2270-1.The interposer 2294 package (comprising, for example, the PIC 2204 andone or more EICs 2270) may be disposed on and electrically connected toa package substrate 2278 (e.g., MCM substrate). Additional componentsmay be disposed on the package substrate 2278. Referring to FIG. 22 ,EIC 2270-2 (e.g., processor, GPU, DPU, CPU, switching unit) may bedisposed on and electrically connected to package substrate 2278 (e.g.,MCM substrate). Package substrate 2278 may comprise circuitry tointerconnect the interposer 2294 and the EIC 2270-2. One or moreadditional EICs 2270 may similarly be integrated with the system.Package substrate 2278 may also comprise circuitry to connect theinterposer (and its hosted components) and the EIC 2270-2 to one or moreadditional components. Referring to FIG. 21 , package substrate 2278 maybe packaged with (e.g., disposed on an electrically connected to) a PCB2298. One or more package substrates 2278 and/or components (e.g., EIC2270, PIC 2204) may be stacked and one or more additional components(e.g., EIC 2270, ASIC, PIC 2204) may be laterally included at each stacklayer. FIG. 21 depicts the electro-optical package with a packagesubstrate and a PCB. Alternatively, the PCB 2298 may take the place ofthe package substrate 2278.

The various components may be electrically connected variously.Referring to FIG. 21 , PIC 2204 and EIC 2270-1 may be electricallypackaged on interposer 2294 with micro bumps allowing for dense I/Os forconnection of components hosted on interposer 2294. Interposer 2294 maybe electrically packaged on package substrate 2278 with, for example,bumps (e.g., C4 bumps). Package substrate 2278 may be electricallypackaged with PCB via, for example, solder balls (e.g., a BGA). Opticalcoupler 2200 (for example, optical coupler as described herein withrespect to FIGS. 1-18 ) may be connected to PIC 2204. Though not fullydepicted for clarity of depiction and description in FIG. 22 , it shouldbe understood that optical coupler 2200 may comprise first opticalelements 2251 (e.g., first turning mirror 120 and/or second curvedmirror 112). Additionally, corresponding second optical elements 2253(e.g., first curved mirror 110, TCM photonic bump 1664, taperedwaveguide photonic bump 1870, grating coupler photonic bump 1764, and/orone or more PIC I/O interface elements (e.g., PIC I/O waveguide 1662)may be integrated with and/or variously added to PIC 2204. Additionally,optical coupler 2200 may comprise one or more of PhotonicPlug layer(e.g. PhotonicPlug layer 106) and spacer layer (e.g., spacer layer 108)to facilitate optical coupling of one or more optical components (e.g.,optical fiber 2202, laser, PIC, and/or chiplet, etc.) to the PIC 2204.

FIG. 23 depicts an example electro-optical package according to one ormore aspects of the present disclosure. Referring to FIG. 23 , Tx PIC2304A and Rx PIC 2304B (generally PIC 2304) may be packaged oninterposer 2394. Alternatively, Tx and Rx PICs 2304A and 2304B may bepackaged on any package substrate (e.g., PCB, MCM, etc.). Tx and Rx PICs2304A and 2304B may be arranged and oriented on the underlying substrate(e.g., interposer) variously. Referring to FIG. 23 , as describedherein, each of PICs 2304A and 2304B may comprise PIC I/O waveguide2362A and 2362B respectively (generally 2362). PICs 2304 may be orientedon interposer 2394 (e.g., underlying substrate) such that the PIC I/Owaveguide 2362 is on the top side of the PIC 2304 (e.g., SiPh chip)(e.g. facing up geometry). As a consequence of the facing up geometry,optically connecting to the PIC 2304 with a facing up geometry maytraditionally be associated with increased ease of connection. Such aconnection, utilizing aspects of the optical couplers herein, aredescribed herein.

Optical couplers 2300A and 2300B (for example, optical coupler asdescribed herein with respect to FIGS. 1-18 ) may be connected to PICs2304A and 2304B respectively. Though not fully depicted for clarity ofillustration in FIG. 23 , it should be understood that optical couplers2300A and 2300B may each comprise first optical elements 2351A and 2351Brespectively (e.g., first turning mirror 120 and/or second curved mirror112). Additionally, corresponding second optical elements 2353A and2353B (e.g., first curved mirror 110, TCM photonic bump 1664, taperedwaveguide photonic bump 1870, grating coupler photonic bump 1764, and/orone or more PIC I/O interface elements (e.g., PIC I/O waveguide 1662)may be integrated with and/or variously added to PICs 2304A and 2304Brespectively. Additionally, optical couplers 2300A and 3200B may eachcomprise one or more of PhotonicPlug layer (e.g. PhotonicPlug layer 106)and spacer layer (e.g., spacer layer 108) to facilitate optical couplingof one or more optical components (e.g., optical fibers 2202A and 2202B,lasers, PICs, and/or chiplets, etc.) to the PICs 2304A and 2304B.

FIG. 24 depicts an example electro-optical package according to one ormore aspects of the present disclosure. Depending on configuration andoptical connection method, as described, facing up geometry may, attimes, be associated with optical connectivity advantages. Referring toFIG. 24 , PIC 2404 may be packaged on interposer 2494 (and/or packagesubstrate 2478 (e.g., organic substrate, MCM substrate, etc.) with thePIC I/O waveguide 2462 near the bottom side (e.g., closer to the sidefacing the underlying substrate (e.g., interposer 2494). Such anarrangement may be referred to as facing down geometry. Facing downgeometry may allow for improved high-speed electrical connectivity ofthe PIC 2404 to the underlying substrate (e.g., interposer 2494), assuch an arrangement may bring the components in closer proximity.However, traditionally, optically connecting to a PIC in face downgeometry has posed a number of issues. For example, optically connectingto the PIC 2404 may be associated with increased challenges as the PICI/O waveguide 2462 is face down (e.g., facing the surface of anunderlying substrate). This challenge is especially apparent with sidecoupling methods. However, as described, aspects of the presentdisclosure relate to separating the plane of the PIC I/O interface (inthis example, PIC I/O waveguide 2462) and the optical component (e.g.,optical fibers) to which the PIC may be optically connected.Accordingly, optical connectors of the present disclosure (e.g., opticalconnectors as described in FIGS. 1-18 ) may be used to connect to facedown PICs by backside coupling. Accordingly, referring to FIG. 24 , theoptical connector (e.g., PhotonicPlug layer and spacer layer) may beinstalled to the backside of the face down PIC 2404. Additionallyaspects of backside coupling are described herein in more detail (forexample with reference to FIGS. 37-45 ).

Optical coupler 2400 (for example, optical coupler as described hereinwith respect to FIGS. 1-18 ) may be connected to PIC 2404. Though notfully depicted in FIG. 24 for clarity of depiction and description, itshould be understood that optical coupler 2400 may comprise firstoptical elements 2451 (e.g., first turning mirror 120 and/or secondcurved mirror 112). Additionally, corresponding second optical elements2453 (e.g., first curved mirror 110, TCM photonic bump 1664, taperedwaveguide photonic bump 1870, grating coupler photonic bump 1764, and/orone or more PIC I/O interface elements (e.g., PIC I/O waveguide 1662)may be integrated with and/or variously added to PIC 2404. Additionally,optical coupler 2400 may comprise one or more of PhotonicPlug layer(e.g. PhotonicPlug layer 106) and spacer layer (e.g., spacer layer 108)to facilitate optical coupling of one or more optical components (e.g.,optical fiber 2402, laser, PIC, and/or chiplet, etc.) to the PIC 2404.Additionally or alternatively, as depicted in FIG. 24 , the substrate ofPIC 2404 may act as and/or be configured similarly to the spacer layer(as described more fully herein).

Referring again to FIG. 23 , electro-optical packages may comprise TxPIC 2304A for transmitting optical signals. Tx PIC 2304A may be disposedon and electrically packaged with interposer 2394. Accordingly, outgoing(e.g., transmitted) optical signals may be transmitted from theelectro-optical package at the Tx PIC 2304A. Tx optical fibers 2302A(and/or alternative optical components, e.g., waveguides, lasers, etc.)may be connected to Tx optical coupler 2300A as described herein withrespect to optical couplers. Tx optical coupler 2300A may be connectedto Tx PIC 2304A to optically coupler the Tx optical fibers 2302A to theTx PIC 2304A according to aspects of optical couplers of the presentdisclosure (for example as described with respect to FIGS. 1-18 ). Theelectro-optical package may further comprise Rx PIC 2304B for receivingoptical signals. Rx PIC 2304 may similarly be disposed on andelectrically packaged with interposer 2394. Accordingly, incomingoptical connections may be received by the package at the Rx PIC 2304B.Rx optical fibers 2302 (and/or alternative optical components, e.g.,waveguides, lasers, etc.) may be connected to Rx optical coupler 2300Baccording to aspects described herein. Rx optical coupler 2300B may becoupled with Rx PIC 2304B according to aspects of the presentdisclosure. EIC 2370-1 (e.g., TIA, driver) may additionally be disposedon and electrically packaged with interposer 2394. Further, one or moreEICs may additionally be disposed on and electrically packaged withinterposer 2394. Interposer 2394 may comprise circuitry to electricallyinterconnect Rx PIC 2304B, Tx PIC 2304A and EIC 2370-1. Additionally,interposer 2394 may comprise circuitry and electrical connectioninfrastructure to electrically connect interposer hosted components(e.g., Rx PIC, Tx PIC, EIC, etc.) with one or more components.

According to other aspects of the present disclosure, signal receptionand transmission may be accomplished with the same PIC. Alternatively,optical signal reception and transmission may be accomplished viadifferent PICs (and/or different chiplets) on different interposers(e.g., Rx interposer and Tx interposer). The Rx and Tx interposers mayin turn be electrically packaged or otherwise electrically connected.For example, the Rx and Tx interposers may be electrically packaged withan underlying substrate 2378 (e.g., MCM, organic substrate). Theunderlying substrate 2378 (e.g., MCM, organic substrate) may allow forelectrical interconnection, and intraconnection, of the Rx and Txinterposers.

As described herein, lasers may be included in optical and/orelectro-optical systems as optical components. Lasers may be used inoptical and electro-optical systems to facilitate communication. Lasersmay, for example, have a role in the conversion and/or translation ofelectrical signals to optical signals. Additionally or alternatively,lasers may be used to variously optically communicate. As describedhereinbelow, lasers may be on-chip or off-chip. For example, referringto FIG. 23 , PIC 2304 may comprise on-chip laser 3277 (e.g., a laserdie). On-chip laser 3277 may for example produce optical signals inresponse to electrical signals (on-chip laser 3277 may produce suchoptical signals in conjunction with various other optical and electricalelements). On-chip laser 3277 may emit optical signals to PIC I/Owaveguide 2362A. The signal, may propagate through the coupler, forexample, via second optical elements 2353A and first optical elements2351A, and may be coupled to an optical component, for example, opticalfiber 2302A. While one configuration of an on-chip laser has beendescribed with respect to FIG. 23 , it would be appreciated by personsof ordinary skill in the art that various configurations of on-chip andoff-chip lasers may be integrated with optical and electro-opticalsystems utilizing one or more aspects of the present disclosure.Off-chip lasers may be described in more detail below.

FIG. 25 depicts an example electro-optical package according to one ormore aspects of the present disclosure. As described, PICs having facingup geometry may be associated with advantages for optical coupling tothe PIC (e.g., it may be simpler to optically couple optical fibers tofacing up geometry PICs), and PICs having facing down geometry may beassociated with electrical advantages (e.g., the electrical componentsmay be closer to the underlying substrate (e.g., interposer) for fasterelectrical connection). Referring to FIG. 25 , the present disclosuremay be practiced with thinned PIC 2504. Thinned PIC 2504, may be, forexample, from 100-200 micron thick. Thinned PIC 2504 may comprise theadvantages of facing up and facing down geometries. For instance,thinned PIC 2504 may comprise PIC I/O waveguide 2562. PIC I/O waveguide2562 may be near the top side of thinned PIC 2504. Accordingly, PIC I/Owaveguide 2562 may be associated with the advantages of opticallycoupling to a PIC having facing up geometry. Additionally, due to thereduced thickness of thinned PIC 2504, optical elements of thinned PIC2504 may be advantageously connected to other package components (e.g.,interposer 2594). For example, thinned PIC 2504 may comprise TSVs 2556to effectuate high speed electrical connection of the thinned PIC 2504and the interposer 2594.

Optical coupler 2500 (for example, optical coupler as described hereinwith respect to FIGS. 1-18 ) may be connected to PIC 2504. Though notfully depicted in FIG. 25 for clarity of depiction and description, itshould be understood that optical coupler 2500 may comprise firstoptical elements 2551 (e.g., first turning mirror 120 and/or secondcurved mirror 112). Additionally, corresponding second optical elements2553 (e.g., first curved mirror 110, TCM photonic bump 1664, taperedwaveguide photonic bump 1870, grating coupler photonic bump 1764, and/orone or more PIC I/O interface elements (e.g., PIC I/O waveguide 1662)may be integrated with and/or variously added to PIC 2504. Additionally,optical coupler 2500 may comprise one or more of PhotonicPlug layer(e.g. PhotonicPlug layer 106) and spacer layer (e.g., spacer layer 108)to facilitate optical coupling of one or more optical components (e.g.,optical fiber 2502, laser, PIC, and/or chiplet, etc.) to the PIC 2504.

The package substrates may be variously arranged to accommodate theoptical coupler. FIGS. 26A-26B depict example electro-optical packagesaccording to one or more aspects of the present disclosure. Referring toFIGS. 26A-26B, PIC 2604 may be arranged to overhang the underlyingpackage substrate, here interposer 2694. Referring to FIG. 26A, whetherthe PIC 2604 is configured to be facing up, facing down (opticallyconnected to, for example, via backside coupling), and/or thinned, theoptical coupler 2600A may be coupled to the top-side of the PIC 2604, asdescribed herein. Alternatively, referring to FIG. 26B, whether the PIC2604 is configured to be facing up (and optically connected to, forexample, via backside coupling), facing down, and/or thinned, theoptical coupler 2600B may be coupled to the bottom side of the PIC 2604.Accordingly, utilizing aspects of the present disclosure, opticalcoupling may be advantageously achieved with various configurations.

Optical couplers 2600A and 2600B (for example, optical coupler asdescribed herein with respect to FIGS. 1-18 ) may be connected to PIC2604. Though not fully depicted in FIG. 26 for clarity of depiction anddescription, it should be understood that optical couplers 2600A and2600B may comprise first optical elements 2651 (e.g., first turningmirror 120 and/or second curved mirror 112). Additionally, correspondingsecond optical elements 2653 (e.g., first curved mirror 110, TCMphotonic bump 1664, tapered waveguide photonic bump 1870, gratingcoupler photonic bump 1764, and/or one or more PIC I/O interfaceelements (e.g., PIC I/O waveguide 1662) may be integrated with and/orvariously added to PIC 2604. Additionally, optical couplers 2600A and2600B may comprise one or more of PhotonicPlug layer (e.g. PhotonicPluglayer 106) and spacer layer (e.g., spacer layer 108) to facilitateoptical coupling of one or more optical components (e.g., optical fiber2602, laser, PIC, and/or chiplet, etc.) to the PIC 2604.

According to yet a further alternative, one or more optical couplers2600 may be coupled to a PIC 2604 at both the top and bottom side of thePIC 2604. For example, FIG. 27 depicts an example configuration ofmultiple optical couplers connected to a PIC according to one or moreaspects of the present disclosure. Referring to FIG. 27 , firstPhotonicPlug layer 2706A and first spacer layer 2708A may connect to thetopside of PIC 2704. Accordingly, First PhotonicPlug layer 2706A andfirst spacer 2718A and first, first curved mirror 2710A may connectfirst optical fiber 2702A (e.g., first optical fiber ribbon in threedimensions) to the topside of PIC 2704 at first PIC I/O interface 2728A(e.g., comprising PIC I/O waveguide) (the optical coupler mayalternatively connect the optical component (e.g., optical fiber 2702)to the second PIC I/O interface 2728B via, e.g., backside coupling).Additionally, second optical coupler, for example comprising, secondPhotonicPlug layer 2706B and second spacer layer 2708B may attach to thebottom side of PIC 2704. Accordingly, second PhotonicPlug layer 2706B,second spacer layer 2708B, and second first curved mirror 2710B mayconnect second optical fiber 2702B (e.g., second optical fiber ribbon inthree dimensions) to the bottom side of PIC 2704 at second PIC I/Ointerface 2728B (e.g., comprising PIC I/O waveguide) (the opticalcoupler may alternatively connect the optical component (e.g., opticalfiber 2702) to the first PIC I/O interface 2728A via, e.g., backsidecoupling).

FIG. 28A depicts an example slotted package substrate 2878. FIG. 28Bdepicts a top view of an example electro-optical package with a slottedpackage substrate 2878 according to one or more aspects of the presentdisclosure. FIG. 28C depicts a side view of the example electro-opticalpackage with a slotted package substrate 2878 of FIG. 28B. Referring toFIGS. 28B-28C, PIC 2804 may be electrically packaged with interposer2894 (e.g., package substrate, chiplet). EIC 2870-1 (e.g., TIA, drive,etc.) may similarly be electrically packaged on interposer 2894. PIC2804 and EIC 2870-1 may be electrically packaged with interposer 2894variously as described herein (e.g., micro-bumps). Electro-opticalinterconnection package may further comprise slotted package substrate2878 (e.g., MCM substrate, PCB, organic substrate, etc.). Slottedpackage substrate 2878 may comprise a slot, or cut-out. Interposer 2894may be electrically packaged with slotted package substrate 2878.Interposer 2894 may be packaged with slotted package substrate 2878 suchthat the interposer 2894 spans at least a portion of the slot of slottedpackage substrate 2878. One or more additional components may beelectrically packaged with interposer 2894 and/or slotted packagesubstrate 2878. EIC 2870-2 (e.g., AISC (e.g., processor, CPU, GPU,etc.)) may be electrically packaged with slotted package substrate 2878.One or more additional EICs may be packaged with slotted packagedsubstrate 2878. EIC 2870-2 may be variously electrically packaged withslotted package substrate 2878 as described herein (e.g., solder bumps(e.g., C4 bumps)). Optical coupler 2800 (for example, optical coupler asdescribed herein with respect to FIGS. 1-18 ) may be connected to PIC2804. Though not illustrated in FIGS. 28A-28C, it should be understoodthat optical coupler 2800 may comprise one or more optical componentsfor optical coupling as described herein (e.g., first turning mirror,first curved mirror, second curved mirror, PhotonicPlug layer, and/orspacer layer, etc.). Optical coupler 2800 may optically couple one ormore optical components (e.g., optical fibers 2810, laser, waveguide,etc.) to the PIC 2804.

FIGS. 28A-28C depict PIC 2804, EIC 2870-1, and optical coupler 2800 asbeing packaged to the bottom side of interposer 2894, it should beunderstood that one or more of PIC 2804, EIC 2870, and/or opticalcoupler 2800 may be packaged to the top side of interposer 2894.

Slotted package substrates may be associated with certain packagingadvantages. For example, slotted package substrate 2878 and opticalcouplers of the present disclosure (e.g., optical coupler 2800) mayallow flexibility in optically connecting to the interconnectionpackage. Additionally, slotted package substrate 2878 may allow for morecompact packaging and smaller package footprint. For example, one ormore of PIC 2804 and/or EIC 2870-1 may be disposed within the slot ofslotted package substrate 2878. As such, the space of theinterconnection package may be reduced. FIGS. 28B-28C depict PIC 2804and EIC 2870-1 as being disposed on the same side (the underside) ofinterposer 2894. According to aspects, however, PIC 2804 and EIC 2870-1may be disposed on different sides of interposer 2894. For example, PIC2804 may be disposed on the bottom side and EIC 2870-1 may be disposedon the top side of interposer 2894, or vice versa. Additionally,advantages of the optical coupler of the present disclosure may allowfor great flexibility and increased tolerance when optically connectingto such electro-optical packages. For instance, FIG. 28C depicts opticalcoupler 2800 as being connected to the PIC 2804. Thus it may beunderstood that optical coupler 2800 may comprise a PhotonicPlug layerand a spacer layer installed to PIC 2804 (alternatively, optical coupler2800 may be backside coupled to PIC 2804). However, leveragingadvantages of the present disclosure, (for example that the PIC I/Ointerface and the optical component to which the PIC is connected may bein different planes), various arrangements and/or configurations ofoptical coupling may be realized.

Optical coupler 2800 (for example, optical coupler as described hereinwith respect to FIGS. 1-18 ) may be connected to PIC 2804. Though notfully depicted in FIG. 28 for clarity of depiction and description, itshould be understood that optical coupler 2800 may comprise firstoptical elements 2851 (e.g., first turning mirror 120 and/or secondcurved mirror 112). Additionally, corresponding second optical elements2853 (e.g., first curved mirror 110, TCM photonic bump 1664, taperedwaveguide photonic bump 1870, grating coupler photonic bump 1764, and/orone or more PIC I/O interface elements (e.g., PIC I/O waveguide 1662)may be integrated with and/or variously added to PIC 2804. Additionally,optical coupler 2800 may comprise one or more of PhotonicPlug layer(e.g. PhotonicPlug layer 106) and spacer layer (e.g., spacer layer 108)to facilitate optical coupling of one or more optical components (e.g.,optical fiber 2810 (e.g., one fiber of optical fiber ribbon 2874),laser, PIC, and/or chiplet, etc.) to the PIC 2804.

For example, FIG. 29 depicts a side view of an example alternativeconfiguration of an electro-optical package with a slotted packagesubstrate 2978 according to one or more aspects of the presentdisclosure. Referring to FIG. 29 , the optical coupler 2900 may becoupled to a first side of the interposer 2994 (e.g., package substrate)and the PIC 2904 may be packaged to a second side (e.g., substantiallyopposed to the first side) of the interposer 2994. Such an arrangementallows for increased flexibility of electrically and optically packagingthe various co-packaged components. According to such an arrangement,the interposer, in addition to electrically interconnecting variouscomponents, may facilitate the optical coupler 2900. For example, theinterposer 2994 may additionally act as and/or be configured similarlyto the spacer layer (e.g., similar to, comprised by, and/or comprising,one or more of the spacer layers of the optical couplers as describedwith respect to FIGS. 1-18 ), for example, similar to an optical throughdie via (OTDV) as described below. Accordingly, the optical signalcoupled by the optical coupler 2900 may propagate through the interposer2994. Additionally, the optical coupler 2900 may be similar to, becomprised by, and/or comprise one or more example of PhotonicPlug layersas described herein. The interposer may comprise a portion of materialthat is substantially transparent to visible wavelengths of light andwavelengths of light being coupled (e.g., glass, epoxy, resin, etc.).Alternatively, interposer may be a material that is substantiallytransparent to wavelengths of light being coupled (e.g., infrared (e.g.,at 1300 nm-1550 nm), for example, silicon, as described herein.

Optical coupler 2900 (for example, optical coupler as described hereinwith respect to FIGS. 1-18 ) may be connected to PIC 2904. Though notfully depicted in FIG. 29 for clarity of depiction and description, itshould be understood that optical coupler 2900 may comprise firstoptical elements 2951 (e.g., first turning mirror 120 and/or secondcurved mirror 112). Additionally, corresponding second optical elements2953 (e.g., first curved mirror 110, TCM photonic bump 1664, taperedwaveguide photonic bump 1870, grating coupler photonic bump 1764, and/orone or more PIC I/O interface elements (e.g., PIC I/O waveguide 1662)may be integrated with and/or variously added to PIC 2904. Additionally,optical coupler 2900 may comprise one or more of PhotonicPlug layer(e.g. PhotonicPlug layer 106) and spacer layer (e.g., spacer layer 108)to facilitate optical coupling of one or more optical components (e.g.,optical fiber 2902, laser, PIC, and/or chiplet, etc.) to the PIC 2904.Additionally, as depicted in FIG. 29 , the interposer 2994 may act asand/or be configured similarly to the spacer (e.g., spacer 1518) and/orspacer layer (e.g., spacer layer 1508). Accordingly, the configurationof FIG. 29 may further be understood to comprise OTDV 2988 (as describedin more detail below).

FIG. 30 depicts an example electro-optical package with a partiallyslotted package substrate 3078 according to one or more aspects of thepresent disclosure. FIGS. 28A-29 depict example interconnection packageswith slotted package substrate having a full slot (e.g., full cut-out).Aspects of the present disclosure may be practiced with partiallyslotted packaged substrates 3078. FIG. 30 depicts an electro-opticalinterconnection package substantially similar to the electro-opticalinterconnection package of FIG. 29 , comprising a partially slottedpackage substrate 3078 in place of the slotted package substrate 2978.Partially slotted substrate 3078 may comprise a partial slot in thesubstrate that may not extend through the width of the entire substrate.The partially slotted substrate 3078 may be slotted with a shape toaccommodate the components packaged to the underside of interposer 3094(e.g., PIC 3004, EIC 3070-1). Advantageously, a partial slot may allowfor a more compact package while additionally allowing for improvedinternal circuitry. Further, as the underside of partially slottedpackage substrate 3078 is fully intact (e.g., not slotted), the entiresurface of the underside of partially slotted package substrate may beleveraged for electrical connection (e.g., to additional substratesand/or components).

Optical coupler 3000 (for example, optical coupler as described hereinwith respect to FIGS. 1-18 ) may be connected to PIC 3004. Though notfully depicted in FIG. 30 for clarity of depiction and description, itshould be understood that optical coupler 3000 may comprise firstoptical elements 3051 (e.g., first turning mirror 120 and/or secondcurved mirror 112). Additionally, corresponding second optical elements3053 (e.g., first curved mirror 110, TCM photonic bump 1664, taperedwaveguide photonic bump 1870, grating coupler photonic bump 1764, and/orone or more PIC I/O interface elements (e.g., PIC I/O waveguide 1662)may be integrated with and/or variously added to PIC 3004. Additionally,optical coupler 3000 may comprise one or more of PhotonicPlug layer(e.g. PhotonicPlug layer 106) and spacer layer (e.g., spacer layer 108)to facilitate optical coupling of one or more optical components (e.g.,optical fiber 3002, laser, PIC, and/or chiplet, etc.) to the PIC 3004.Additionally, as depicted in FIG. 30 , the interposer 3094 may act asand/or be configured similarly to the spacer (e.g., spacer 1518) and/orspacer layer (e.g., spacer layer 1508). Accordingly, the configurationof FIG. 30 may further be understood to comprise OTDV 3088 (as describedin more detail below).

FIG. 31 depicts an example electro-optical package with a slottedpackage substrate 3178 according to one or more aspects of the presentdisclosure. Referring to FIG. 31 , electro-optical package may be usedwith heat sinking device 3180. Advantageously, slotted package substrate3178 may allow for the efficient inclusion of heat sinking device 3180.Referring to FIG. 31 , PIC 3104 and EIC 3170-1 may be disposed on theunderside of interposer 3194 (e.g., package substrate). Additionally,the substrates may be arranged such that PIC 3104 and EIC 3170-1 may bedisposed within the slot of slotted package substrate 3178. Heat sinkingdevice 3180 may be installed on the top side of interposer 3194 toassist in thermal management of the components packaged with theinterposer 3194. Additionally, interposer 3194 may comprise TSVs 3156from the topside of interposer 3194 to the underside of the interposer3194. Heat sinking device 3180 may be placed on top of TSVs 3156 tofurther facilitate thermal management of the components packaged withthe package substrate.

Optical coupler 3100 (for example, optical coupler as described hereinwith respect to FIGS. 1-18 ) may be connected to PIC 3104. Though notfully depicted in FIG. 31 for clarity of depiction and description, itshould be understood that optical coupler 3100 may comprise firstoptical elements 3151 (e.g., first turning mirror 120 and/or secondcurved mirror 112). Additionally, corresponding second optical elements3153 (e.g., first curved mirror 110, TCM photonic bump 1664, taperedwaveguide photonic bump 1870, grating coupler photonic bump 1764, and/orone or more PIC I/O interface elements (e.g., PIC I/O waveguide 1662)may be integrated with and/or variously added to PIC 3104. Additionally,optical coupler 3100 may comprise one or more of PhotonicPlug layer(e.g. PhotonicPlug layer 106) and spacer layer (e.g., spacer layer 108)to facilitate optical coupling of one or more optical components (e.g.,optical fiber 3102, laser, PIC, and/or chiplet, etc.) to the PIC 3104.Additionally, as depicted in FIG. 31 , the interposer 3194 may act asand/or be configured similarly to the spacer (e.g., spacer 1518) and/orspacer layer (e.g., spacer layer 1508). Accordingly, the configurationof FIG. 31 may further be understood to comprise OTDV 3188 (as describedin more detail below).

FIG. 32 depicts an example electro-optical package with a slottedpackage substrate 3278 according to one or more aspects of the presentdisclosure. Components may be packaged with slotted package substrates3278 variously. Referring to FIG. 32 , interposer 3214 (e.g., packagesubstrate) may be packaged to the underside of slotted package substrate3278. PIC 3204 and EIC 3270-1 (e.g., TIA, driver) may be packaged to thetop side of interposer 3214. Interposer 3214, slotted substrate 3204,PIC 3204 and EIC 3270-1, may be arranged such that PIC 3204 and EIC3270-1 may be disposed within the slot of slotted substrate 3278. Heatsinking device 3280 may be installed on the topside of slotted substrate3278. Further, heat sinking device 3280 may span at least a portion ofthe slot. Advantageously, such an arrangement may simultaneously benefitfrom improved package size and improved thermal management.Particularly, components PIC 3204 and EIC 3270-1 may be arranged in theslot of slotted package substrate 3278 to reduce the size of thepackage, and heat sinking device 3280 may assist with the thermalmanagement of the slotted substrate 3278, the PIC 3204 and EIC 3270-1.Additional components may be included in the package. Referring to FIG.31 , EIC 3270-2 (e.g., ASIC (e.g., processor, CPU, GPU, etc.)) may bepackaged with slotted package substrate 3278. EIC 3270-2 may be packagedwith slotted substrate 3278 as described herein (e.g., solder bumps(e.g., C4 bumps)). One or more additional components (e.g., PICs, EICs,ASICs) may be packaged with slotted substrate 3278 and/or interposer3214. Additionally, one or more components (e.g., PIC, EIC, ASIC,substrate) may be hosted by (e.g., stacked to) one or more components(e.g., PIC 3204, EIC 3270-1, EIC 3270-2, slotted substrate 3278,interposer 3214). The arrangement of the components may additionally bevaried. For example, EIC 3270-2 is depicted as being packaged with thetop side of slotted substrate 3278. According to aspects, EIC 3270-2 maybe packaged with slotted substrate 3278 variously (e.g., to underside ofslotted substrate 3278). According to aspects including multiplecomponents packaged with slotted substrate 3278, components may bepackaged in any combination to the topside and underside of the slottedsubstrate 3278.

Optical coupler 3200 (for example, optical coupler as described hereinwith respect to FIGS. 1-18 ) may be connected to PIC 3204. Though notfully depicted in FIG. 32 for clarity of depiction and description, itshould be understood that optical coupler 3200 may comprise firstoptical elements 3251 (e.g., first turning mirror 120 and/or secondcurved mirror 112). Additionally, corresponding second optical elements3253 (e.g., first curved mirror 110, TCM photonic bump 1664, taperedwaveguide photonic bump 1870, grating coupler photonic bump 1764, and/orone or more PIC I/O interface elements (e.g., PIC I/O waveguide 1662)may be integrated with and/or variously added to PIC 3204. Additionally,optical coupler 3200 may comprise one or more of PhotonicPlug layer(e.g. PhotonicPlug layer 106) and spacer layer (e.g., spacer layer 108)to facilitate optical coupling of one or more optical components (e.g.,optical fiber 3202, laser, PIC, and/or chiplet, etc.) to the PIC 3204.Additionally, as depicted in FIG. 32 , the interposer 3294 may act asand/or be configured similarly to a spacer (e.g., spacer 1518) and/orspacer layer (e.g., spacer layer 1508). Accordingly, the configurationof FIG. 32 may further be understood to comprise OTDV 3288 (as describedin more detail below).

Aspects of the present disclosure relate to the mechanical packaging ofoptical couplers, and mechanical packaging of optical couplers to PICsand other external components. Referring to FIG. 1 , optical coupler maycomprise PhotonicPlug layer 106 and spacer layer 108. PhotonicPlug layermay be mechanically packaged with spacer layer 108. As described herein,one or more bonding agent (e.g., adhesives, epoxies, resins and thelike) may be used to secure optical fibers within receiving features ofreceiving substrate. Similarly, bonding agents (e.g., adhesives,epoxies, resins, and the like) may be used to mechanically packagesubstrates of PhotonicPlug layer 106 to substrates of spacer layer 108.Any bonding agent incorporated at substrate interfaces of the opticalcoupler may be used for bonding as well as an optical medium (throughwhich optical beam may propagate). As such, when selecting bondingagents to be used to bond substrates of the optical coupler, a bondingagent with an appropriate index of refraction may be selected.

FIG. 33A depicts an example electro-optical package with mechanicalaligners according to one or more aspects of the present disclosure.Referring to FIG. 33A, optical coupler 3300 may comprise mechanicalalignment structures to assist mechanical positioning upon opticalcoupler packaging. Such mechanical couplers may assist in positioningsubstrates in the X, Y, and Z directions, as well as the tilt of thesubstrates with respect to one another. Alignment structures may be inthe form of one or more mechanical plugs 3382, and associated mechanicalsockets 3384. The plug 3382 and socket 3384 may comprise complementarygeometry to mechanically interface and engage one another. Any shape ofplug 3382 and socket 3384 is contemplated herein. Additionally, anymethod of mechanical alignment known to those of ordinary skill in theart are contemplated herein.

FIG. 33B depicts an exploded view of the example electro-optical packagewith mechanical aligners of FIG. 33A. Referring to FIG. 33B,PhotonicPlug layer substrate 3326 (e.g., receiving substrate) maycomprise PhotonicPlug plug structures 3382A. Spacer layer substrate(e.g., spacer 3318) may comprise spacer layer socket structures 3384A.Spacer layer socket structures 3384A may correspond to PhotonicPluglayer plug structures 3382A. PhotonicPlug layer plug structures 3382Aand spacer layer socket structures 3384A may comprise complementarygeometry to mechanically engage and interface each other. Upon assemblyof the PhotonicPlug layer substrate 3326 with the spacer layer substrate3318, PhotonicPlug layer plugs 3382A may engage spacer layer sockets3384A to align PhotonicPlug layer substrate 3326 with spacer layersubstrate 3318 as desired. Additionally, Spacer layer substrate (e.g.,spacer 3318) may comprise spacer layer plug structures 3382B. PIC layersubstrate (e.g., SiPh chip, or PIC 3304) may comprise PIC layer socketstructures 3384B. PIC layer socket structures 3384B may correspond tospacer layer plug structures 3382B. Spacer layer plug structures 3382Band PIC layer socket structures 3384B may comprise complementarygeometry to mechanically engage and interface each other. Upon assembly,spacer layer plug structures 3382B may engage with PIC layer socketstructures 3384B to align spacer layer substrate (e.g., spacer 3318)with PIC layer substrate (e.g., PIC 3304) as desired.

Further, PIC 3304 may be packaged with further packaging substrates(e.g., package substrate 3378, e.g., interposer, PCB, MCM, etc.)Accordingly, it may be desirable to mechanically align PIC 3304 (e.g.,SiPh chip) with the underlying package substrate 3378. Accordingly, PIC3304 may comprise PIC plug structures 3382C and package substrate maycomprise package substrate socket structures 3384C. PIC plug structures3382C may correspond to package substrate socket structures 3384C. PICplug structures 3382C and package substrate socket structures 3384C maycomprise complementary geometry that may mechanically engage andinterface with each other. Upon assembly of PIC 3304 on underlyingpackage substrate 3378, PIC plug structures 3382C may engage packagesubstrate socket structures 3384C to align PIC 3304 on package substrate3378 as desired.

As would be understood by persons of ordinary skill in the art, all plugstructures and socket structures are depicted and described as examplestructures for purposes of discussion. Accordingly, all plug structuresmay be replaced with socket structures and socket structures may bereplaced with plug structures. Additionally, the same substrate maycomprise any number of plug structures and any number of socketstructures in any combination. Further, as would be understood bypersons of ordinary skill in the art, plug structure and correspondingsocket structures may be shaped variously. For example, plug structuresmay be, for example, spherical, rod shaped, square peg shaped, trianglepeg shaped, etc. Socket structures may comprise any complimentarygeometry to plug structures to allow the plug structure to engage thesocket structures.

Plug structures and socket structures may be fabricated variously. Forexample, according to aspects, plug structures and socket structures maybe fabricated through die level or wafer level processed, for example,NIL, grayscale lithography, CMOS, etc. Additionally or alternatively,plug structures and socket structures may be fabricated variously forexample, plastic injection, hot embossing, metal stamping, or otheraccurate machining processes.

As will be appreciated, it may be desirable to retain an appropriateindex of refraction at the interface of different substrates andmediums. Accordingly, the surfaces at the interfaces between some or allmedia may be treated with an anti-reflective layer (e.g., coating) asdescribed above with reference to FIG. 7A. Referring to FIG. 33B,anti-reflective layers 3352A-3352D (generally 3352) may be illustratedas dotted lines at substrate and layer interfaces. Accordingly, aPhotonicPlug layer substrate 3326 (e.g., receiving substrate) mayinterface with a spacer substrate (e.g., spacer 3318). Accordingly,anti-reflective layer 3352A may be added to PhotonicPlug layer substrate3326 at the PhotonicPlug layer-spacer layer interface. Additionally oralternatively, anti-reflective layer 3352B may be added to the spacerlayer substrate 3318 at the PhotonicPlug layer-spacer layer interface.Further, spacer layer substrate 3318 may interface with PIC layersubstrate (e.g., PIC 3304). Accordingly, anti-reflective layer 3352C maybe added (e.g., deposited) to the spacer layer substrate 3318 at thespacer layer-PIC layer interface. Additionally or alternatively,anti-reflective coating 3352D may be added to the PIC layer substrate(e.g., PIC 3304) at the spacer layer-PIC layer substrate.

According to aspects, as described herein, a single layer, e.g., spacerlayer, may comprise more than one substrate. As such, it may similarlybe desirable to add an anti-reflective layer to the substrate interfacewithin a single optical coupler layer. For example, referring to FIG.7A, spacer layer may comprise first spacer substrate and second spacersubstrate. It may be desirable to add anti-reflective layer to eitherthe first spacer substrate or second spacer substrate, or to addanti-reflective layer to both first spacer substrate and second spacersubstrate at the first spacer substrate-second spacer substrateinterface.

Additionally, according to aspects, one or more air gaps may be presentin the optical coupler package (see for example, FIG. 52 ). Accordingly,one or more anti-reflective layers may be deposited on one or more ofthe surfaces at such an air gap interface.

Many aspects of the present disclosure have been illustrated withrespect to a fiber-to-chip connectivity. While all aspects illustratedas fiber-to-chip connectivity are contemplated as for chip-to-chipconnectivity as well, some aspects of chip-to-chip connectivity may beillustrated and more easily understood. As discussed, advanced computing(e.g., distributed computing, accelerated computing, high performancecomputing) for applications such as, for example, cloud computing,machine learning computing, or other heavy workloads, may require and/orbenefit from high bandwidth, low power consumption and low latency. Muchof the power consumption in state-of-the-art computing systems isconsumed on electrical I/Os. Optical I/Os consume less power, scale upbandwidth, and improves latency performance. Therefore, there is ademand to replace copper connectivity between processors (e.g., GPU toGPU) and other chips with optical connectivity.

Chip-to-chip connectivity may benefit from successful integrationbetween optical and electrical packaging, e.g., die stacking geometry,passive assembly, large assembly tolerances, compatibility with 2.5D and3D packaging platforms including flip-chip packaging and reflowprocesses. Optical couplers and photonic bumps of the present disclosurecomply with the above advantageous opto-electrical packaging, andproduction processes. Further advantageously, aspects of the photonicbumps, as described herein may enable wafer optical bumping and flexiblephotonics packaging. Additionally, aspects of the photonic bumps mayenable optical through die vias (OTDV), and optical electricalinterposes for 2.5D and 3D packaging.

FIG. 34A depicts an example chip-to-chip optical connectivity schemeaccording to one or more aspects of the present disclosure. Referring toFIG. 34A, EIC 3470-1 (e.g., ASIC (e.g., processor, GPU, etc.)) may beelectrically packaged with package substrate 3478 (e.g., interposer).EIC 3402-2 (e.g., ASIC) may similarly be electrically packaged withpackage substrate 3478. The connectivity scheme may further comprise afirst optical coupler 3400A and a second optical coupler 3400B. Each ofthe first and second optical couplers may comprise and couple first andsecond PICs 3404A and 3404B. First PIC 3404A may be electricallyconnected to first EIC 3470-1 (discussed in more detail below). Thefirst EIC 3470-1 may be electrically connected to the first PIC 3404(e.g., via wire bonding and/or solder bumps). The first EIC 3470-1 maysend one or more electrical signal to the first PIC 3404A. The first PIC3404A may translate, convert, or otherwise produce an optical signal inresponse to the electrical signal. The optical signal may propagatethrough the first optical coupler 3400A substantially as describedherein with respect to optical couplers (for example with reference toFIGS. 1-18 ). Referring to FIG. 34A. Each optical coupler may comprise afirst curved mirror 3410A and 3410B (generally 3410), and a secondcurved mirror 3412A and 3412B (generally 3412). First curved mirrors maybe fabricated on and/or added to package substrate 3478. Additionally,each optical coupler 3400 may comprise a first turning mirror 3420A and3420B (generally first turning mirror 3420). Each PIC 3404 may comprisea first PIC I/O waveguide 3462A and 3462B generally PIC I/O waveguide3462). As such, optical signals 3416A and 3416B may propagate to/fromfirst and second PIC I/O waveguides 3462A and 3462B respectively throughthe first and second optical couplers 3400A and 3400B respectivelysubstantially as described herein. The optical signals 3416 maypropagate from first PIC I/O waveguide 3462A to first turning mirror3420A and be incident on first turning mirror 3420A. The optical signal3416A may be expanding as it propagates from the first PIC I/O waveguide3462A and first turning mirror 3420A. First turning mirror 3420A maydirect the expanding optical signal 3416A at the first, first curvedmirror 3410A. The first, first curved mirror 3410A may substantiallycollimate the optical signal 3416A and reflect and direct thesubstantially collimated optical signal 3416A at the first, secondcurved mirror 3412A. The first, second curved mirror 3412A maysubstantially focus the optical signal 3416A and reflect and direct thefocusing optical signal 3416A toward first interconnect waveguide I/O3484A.

As described with respect to optical couplers herein, first curvedmirrors 3410 may be fabricated in, fabricated on, or otherwiseintegrated with package substrate 3478. Alternatively, first curvedmirrors 3410 may be integrated with the spacer layer. Alternatively,first curved mirror 3410 may be integrated with the PIC substrate.Alternatively, first curved mirrors 3410 may be integrated with anyadditional substrate as would be understood from the present disclosure.Second curved mirrors 3412 may be fabricated in, fabricated on, orotherwise integrated with the substrate of the PIC 3404. Alternatively,second curved mirrors 3412 may be integrated with spacer layer.Alternatively, second curved mirrors 3412 may be integrated with packagesubstrate 3478. Alternatively, second curved mirrors 3412 may beintegrated with any additional substrate as would be understood from thepresent disclosure. Additionally, as would be understood from thepresent disclosure, for example, like aspects as described with respectto FIG. 8 , the optical couplers may not include first turning mirrors3420.

The connectivity scheme may comprise an interconnect waveguide 3486. Theinterconnect waveguide may be, for example, a polymer waveguide, asilicon waveguide (e.g., silicon-on-insulator), or any other suitableoptical waveguide as would be understood by persons of ordinary skill inthe art. The interconnect waveguide may be fabricated in and/orfabricated on the substrate package 3478 (e.g., interposer). Theinterconnect waveguide 3486 may route variously through the packagesubstrate 3478 to optically connect various components thereon. Theinterconnect waveguide 3486 may optically connect the first opticalcoupler 3400A to the second optical coupler 3400B. Each optical couplermay comprise an interconnect waveguide I/O element 3484. Theinterconnect waveguide I/O elements 3484 may comprise, for example, TCMphotonic bump elements as described with reference to FIGS. 16A-16E,and/or tapered waveguide photonic bump elements as described withreference to FIGS. 18A-18C. Additionally or alternatively, theinterconnect waveguide I/O elements may comprise additional oralternative optical elements for example grating couplers.

Still with reference to FIG. 34A, the optical signal may propagatethrough the interconnect waveguide 3486 to second interconnect waveguideI/O element 3484B (e.g., TCM photonic bump, tapered waveguide photonicbump, grating coupler, etc.). The optical signal may propagate from thesecond interconnect waveguide I/O element 3484B and may be directed tothe second, second curved mirror 3412B. The optical signal 3416B (whichmay be the same signal as 3416A at a different location) may besubstantially divergent as it propagates from the interconnect waveguide3486 and from the second interconnect waveguide I/O element 3484B.Second, second curved mirror 3412B may substantially collimate thediverging optical signal 3416B. Second, second curved mirror 3412B mayalso reflect the substantially collimated optical signal 3416B anddirect the substantially collimated optical signal 3416B toward thesecond, first curved mirror 3410B of the second optical coupler. Thesecond, first curved mirror 3410B may substantially focus the opticalsignal 3416B and reflect and direct the substantially focusing opticalsignal toward the second, first turning mirror 3420B, of the secondoptical coupler. The second, first turning mirror 3420B, of the secondoptical coupler may reflect the focusing optical signal 3416B and directthe focusing optical signal 3416B to the second PIC I/O waveguide 3462B.The second PIC 3404B may convert, transform, and/or translate theoptical signal into one or more electrical signals. The second PIC 3404Bmay be electrically connected to the second EIC 3470-2 (described inmore detail). As would be readily understood from the presentdisclosure, the signal propagation as depicted in FIG. 34A has beendescribed as propagating from the first EIC 3470-1 (and the firstoptical coupler 3400) to the second EIC 3470-2 (and the second opticalcoupler 3400). As would be understood by persons of ordinary skill inthe art, the scheme may operate in reverse (e.g., the second EIC 3470-2and second optical coupler 3400B may transmit the optical signal and thefirst optical coupler 3400A and first EIC 3470-1 may receive the opticalsignal). Utilizing the aspects of such a scheme, the first EIC 3470-1may be optically connected to the second EIC 3470-2. Accordingly,package substrate 3478 (e.g., interposer) may comprise elements foroptical connection (e.g., optical channel, optical fiber, interconnectwaveguide, etc.) and may comprise elements for electrical connection(e.g., electrical traces, pads, TSVs, etc.).

FIG. 34B depicts an example chip-to-chip optical connectivity schemeaccording to one or more aspects of the present disclosure. FIG. 34Adepicts chip-to-chip on substrate optical connectors having a separatespacer (e.g., glass, epoxy, silicon), for example, spacers as describedherein with reference to FIG. 1 . With reference to FIG. 34B, thepackage substrate 3478A (e.g., interposer) may additionally act asand/or be configured similarly to a spacer. Accordingly, the packagesubstrate 3478A may comprise electrical through silicon vias (TSV) 3456(e.g., where the package substrate is fabricated of silicon material)and/or electrical through glass vias (TGV) 3456 (e.g., where the packagesubstrate is fabricated of silicon material). Additionally oralternatively, the package substrate may further comprise opticalthrough die vias (OTDV) 3488. Electrical TSVs and/or TGVs may facilitateelectrical connection of one component to another and OTDVs 3488 mayfacilitate optical connection of one component to another. Optical TDVs3488 may comprise elements, for example elements described herein, tooptically connect optical components according to the presentdisclosure. For example, Optical TDVs 3488 may each comprise a curvedmirror 3410. Optical TDV curved mirror 3488 may operate substantially asdescribed herein in relation to curved mirrors (for example as describedin relation to first curved mirrors for example of FIGS. 1-18 and 34A.Optical TDV curved mirror 3488 may, for example, substantially reflectoptical signals, and may be a focusing element that may substantiallyfocus and/or substantially collimate optical signals depending ondirection of propagation. Additionally, OTDVs 3488 may comprise one ormore elements of a photonic bump as described herein. For example, theinterconnect waveguide I/O elements 3484 may comprise for example,tapered waveguide and flat turning mirror (for example as describedherein with respect to the tapered waveguide photonic bump of FIGS.18A-18C), or a TCM photonic bump (for example, as described herein withrespect to FIGS. 16A-16E). Additionally or alternatively, interconnectwaveguide I/O elements may be included and/or fabricated substantiallyas described in relation to backside coupling of FIGS. 37-45 .Additionally or alternatively, interconnect waveguide I/O elements maycomprise additional or alternative optical elements, for example,grating couplers.

Referring to FIG. 34B, EIC-1 3470-1 may be electrically connected (via,e.g., electrical traces 3490A) to the first PIC 3404A. EIC-1 3470-1 mayproduce one or more electrical signals. The first PIC 3404A may receivethe electrical signal. The first PIC 3404A may variously produce anoptical signal in response to the electrical signal received from EIC-13470-1. The first PIC may transmit the optical signal, e.g., from firstPIC I/O waveguide to first, first turning mirror 3420A. The opticalsignal may propagate from the first, first turning mirror, of the firstPIC 3404A, into the first TDV 3488A. The optical signal may propagatethrough the first TDV 3488A substantially as described in relation tooptical signal propagation in optical couplers herein. The opticalsignal may propagate from the first OTDV first curved mirror 3410A tothe first, second curved mirror 3412A, and from the first, second curvedmirror 3412A to the first interconnect waveguide I/O 3484A. The opticalsignal may propagate through the interconnect waveguide 3486 (e.g.,polymer waveguide) and exit the waveguide at the second interconnectwaveguide I/O 3484B at the second OTDV 3488B. The optical signal maypropagate from the second interconnect waveguide I/O 3484B to thesecond, second curved mirror 3412B, of the second PIC 3404B. The opticalsignal may propagate from the second, second curved mirror 3412B to thesecond OTDV curved mirror 3410B. The optical signal may propagate fromthe second OTDV curved mirror 3410B to the second, first turning mirror3420B, and from the second, first turning mirror into the second PIC I/Owaveguide 3462B. The second PIC 3404B may, in response to receiving theoptical signal, produce one or more electrical signals. The second PIC3404B may be in electrical connection and/or communication (via, e.g.,electrical traces 3490B) with EIC-2 3470-2. The PIC 3404B maycommunicate the one or more electrical signals, produced in response tothe optical signal, to EIC-2 3470-2. Accordingly, EIC-1 3470-1 may beoptically connected to EIC-2 3470-2 via the example configurationdepicted in FIG. 34B.

One or more additional components and/or substrates may be packaged withthe components of FIG. 34B. For example, the electro-optical package mayfurther comprise a second substrate 3478B. The second substrate 3478Bmay host one or more other components (e.g., EIC-3 3460-3), and mayfacilitate electrical and/or optical connection of one or morecomponents packaged on package substrate 3478A and/or second substrate3478B.

FIG. 35 depicts a plurality of example TCM photonic bumps 3564 (thoughFIG. 35 depicts a plurality of example TCM photonic bumps 3564, only oneTCM photonic bump is referenced with numeral 3564 for clarity ofillustration) and optical waveguides according one or more aspects ofthe present disclosure. Referring to FIG. 35 , each TCM photonic bump3564 may also be considered an optical via. Each TCM photonic bump 3564may comprise a TCM 3560 and a TCM PB curved mirror 3512. Additionally,each TCM 3560 may correspond to waveguide 3562 (e.g., a polymerwaveguide, silicon on insulator waveguide, etc.). The waveguides may beexample of PIC I/O waveguides (e.g., PIC I/O waveguide 1662) and/orinterconnect waveguide (e.g., interconnect waveguides 3486). As may beappreciated, one or more optical couplers may be disposed over theplurality of TCM photonic bumps 3564. The optical couplers may compriseoptical elements (e.g., a curved mirror and a turning mirror)corresponding to each of the plurality of TCM photonic bumps 3564. Theoptical elements of the optical couplers may be connected to opticalcomponents (e.g., optical fibers, lasers, etc.). Accordingly, utilizingthe TCM photonic bump configuration of FIG. 35 , a dense package ofoptical connection may be realized where each of the plurality of TCMphotonic bumps may be connected to a different optical component. Eachwaveguide 3562 may be connected to a PIC. Additionally or alternatively,each waveguide may terminate (not shown) at the waveguide's other sidein an additional TCM photonic bump 3564.

With reference to FIGS. 34A and 34B it may be appreciated that asubstrate may comprise a plurality of interconnect waveguides and aplurality of PICs and EICs to optically connect any number of EICs orother electrical components. FIG. 36A depicts an example electro-opticalpackage according to one or more aspects of the present disclosure.Referring to FIG. 36A, an electro-optical package may comprise a packagesubstrate 3678 (e.g., interposer). Package substrate 3678 may beelectrically and optically packaged with various components. Referringto FIG. 36A, EIC-1 3470-1, EIC-2 3470-2, EIC-3 3470-3, and EIC-4 3470-4(EIC-1-EIC-4 may be examples of ASICS (e.g., processors e.g., CPU, DPU,etc.) and may be packaged with and/or on package substrate 3678. Furthercomponents may be packaged. Referring to FIG. 36A, for example HBMs 3692may be associated with each EIC. HBMs 3692 may be packaged in proximityto the EIC with which they are associated. Each EIC and associated HBMmay be electrically connected to each other via package substrate 3678-1(e.g., with package substrate circuitry, e.g., electrical traces).Additionally, each EIC 3670 may be associated with a chiplet 3605.chiplets 3605 may be electrically connected to their associated EIC.Thus, EIC-1 3670-1 may be electrically connected to chiplet-1 3605,EIC-2 3670-2 may be electrically connected to chiplet-2 3605-2, EIC-33670-3 may be electrically connected to chiplet-3 3605-3, and EIC-43670-4 may be electrically connected to chiplet-4 3605-4, etc. chiplets3605 may comprise components to convert electrical signals to opticalsignals, and to convert optical signals to electrical signals.

Chiplets 3605 may be optically connected to one another. Referring toFIG. 36A, chiplets 3605 may be optically interconnected via opticalinterconnect waveguides 3686, for example, polymer waveguide 3686. FIG.36A depicts a plurality of optical waveguide 3686 (as lines) connectingoptical couplers 3600 (not all optical interconnect waveguides 3686 arereferenced with numeral 3686 for clarity of illustration). The opticalinterconnect waveguides 3686 may be fabricated in and/or on the packagesubstrate 3678. Alternatively, a separate waveguide interposer may beincluded and packaged on top of package substrate 3678. Accordingly, allEICs 3670 on the package substrate 3678 may be optically interconnected(for example as depicted in FIGS. 34A and 34B). The interconnectwaveguides 3686 may be connected to the chiplets 3605 via opticalcouplers 3600 of the present disclosure. As will be appreciated, asingle optical coupler 3600 may comprise the elements to connect aplurality of optical interconnect waveguides 3686. It should beappreciated that some or all of the optical interconnect waveguides 3686may be replaced by optical fibers.

Referring to FIG. 36A, package substrate 3678 may comprise one or moreadditional groups of components. As such it may be advantageous to routeoptical signals from one group of components to another. Referring toFIG. 36A, optical terminal 3694 may be packaged with package substrate3686. Optical terminal 3694 (e.g., laser, PIC), may receive and routeoptical signals from one group of optical engines (e.g., PICs) to otheroptical engines (e.g. PICs). Additionally, it may be advantageous tooptically interconnect the package substrate 3678-1 itself (e.g., thepackage substrate), where the components on the package substrate, andthe package substrate, may be optically connected with other opticalcomponents. Thus, the optical terminal may further comprise off-boardoptical connections. For example, one or more optical fibers may beconnected to optical terminal 3694 via one or more optical couplers 3600disclosed herein. The package substrate 3678-1 may comprise any numberof optical terminals 3694. Each optical terminal 3694 may be opticallyconnected to any number of off-board optical connections. For example,the optical terminal 3694 may facilitate connection to one or more ofadditional package substrates 3678-2 and/or 3678-3. Package substrates3678-2 and 3678-3 may be substantially similar to package substrate3678-1.

As described above, aspects of the present disclosure relate tooptically interconnecting substrates using the couplers of the presentdisclosure. FIG. 36B depicts an example electro-optical packageaccording to one or more aspects of the present disclosure. For example,referring to FIG. 36B, multiple electro-optical (and/or optical)substrates 3678 may each be connected with an interconnect substrate3696. Each package substrate 3678 may be an example of the packagesubstrates 3678 of FIG. 36A. Interconnect substrate 3696 may, forexample, operate as a server rack as well as an interconnect substrate.Interconnect substrate may additionally comprise interconnect waveguides3686 to interconnect one or more package substrates 3678 and/orcomponents that are optically connected to the interconnect substrate.

As described above, aspects of the present disclosure relate to backsidecoupling which may described herein in more detail. To provide forsimplicity of description, the “bottom” of the SiPh chip may be referredto herein to the bottom surface of the SiPh chip prior to the SiPh chipbeing flipped. The bottom surface of the SiPh chip may be the surface ofthe SiPh chip opposite that on which the optical circuitry is developed.Similarly, for simplicity of description, the “top” of the SiPh chip maybe referred to herein to the top surface of the SiPh chip prior to theSiPh chip being flipped. The top surface of the SiPh chip may be thesurface of the SiPh chip on which the optical circuitry is developed.

The thickness of the optical chip may be turned from a disadvantage toan advantage for a flip-chip mounted SiPh chip by a unique structure andarrangement of optical components including a photonic plug so thatlight from an optical fiber (e.g., SMF) that is coupled to a SiPh chipmay pass through a portion of the thickness of the SiPh chip'ssubstrate. To this end, a cavity may be etched out of the top of thesubstrate of the SiPh chip. The area of the SiPh chip from which acavity may be etched (and optical components may be formed, as describedherein) may be referred to as an example of a photonic bump. A tiltedflat mirror and a curved mirror may be formed by stamping and curing animprint material placed in and possibly over the cavity forming theexample photonic bump. A photonic plug comprising, for example, a tiltedflat mirror and a curved mirror may be placed over a spacer which inturn may be placed over the bottom of the flipped SiPh chip in the areaof the photonic bump. The one or more fibers for which light is to becoupled with the SiPh chip may be fixed to the photonic plugsubstantially as described herein. The resulting optical path may couplelight between the optical fiber and the SiPh chip.

Note that the structures of the photonic bump portion of the SiPh chipneed not be manufactured at the same time that the SiPh chip ismanufactured. Therefore, the structures of such a photonic bump can beadded by another party, e.g., a party who did not manufacture the restof SiPh chip, possibly, at a later time.

The bottom of the SiPh chip and the photonic plug may be arranged suchthat the photonic plug is detachable from the SiPh chip which will bedescribed in more detail below.

FIG. 37 shows an example method for making a structure and coupling ofsingle-mode fiber to a silicon photonics chip that is flip-chip mountedusing backside optical coupling.

In step 3701, a cavity may be formed in the top of a SiPh chip in thephotonic bump area. The cavity may be formed by etching down from thetop of the SiPh chip. FIG. 38 shows an example cavity 3803 as havingbeen formed in top 3807 of SiPh chip 3801. SiPh chip 3801 already, e.g.,prior to formation of the cavity, may have waveguide 3805 formedthereon. Cavity 3803 may have a depth in the range of 10 to 20 micronswhile it may have a width in a range from 150 microns to a few hundredmicrons. According to one or more aspects, the width may be, forexample, 200 microns. Although only one cavity is shown, it will beappreciated by those of ordinary skill in the art that more than onecavity may be employed, e.g., one cavity per fiber to be coupled to theSiPh chip. Alternatively, one cavity may be employed for more than onewaveguide to be coupled to corresponding fibers. Also shown in FIG. 38is bottom 3809 of SiPh chip 3801. Note that the above references to“backside” optical coupling refer to coupling the light at least oncethrough bottom 3809 of SiPh chip 3801

Referring to FIG. 39 , antireflective coating layers 3911 may be appliedalong the bottom of cavity 3803 and also along a portion of bottom 3809of SiPh chip 3801, at least under the portion of bottom 3809 that isunder cavity 3803, in step 3703. Such antireflective coating may be adielectric material such as a layer of magnesium fluoride, althoughthose of ordinary skill in the art will be able to select anantireflective coating suitable to the materials and structure employedwhich is described further hereinbelow. Advantageously, theantireflective coating layers may substantially overcome the difference,e.g., a mismatch, in the index of refraction as light propagates fromone medium to another. Accordingly, antireflective coating layers may beused to reduce scattering. Note that the layer of antireflective coating3911 along bottom 3809 of SiPh chip 3801 may be applied at a differenttime, e.g., a later time, than layer of antireflective coating 3911along bottom of cavity.

In step 3705, an imprint material, e.g., a liquid, suitable to be formedby stamping may be deposited on SiPh chip 3801 and at least in cavity3803 thereof. The deposited imprint material may also extend over atleast a portion of top 3807 of SiPh chip 3801. One material that may beused as the imprint material may be a siloxane, which may be obtainedfrom INKRON or other sources which may comprise a UV sensitive resinuseful for nanoimprinting. The imprint material may be such that it issubstantially transparent to light at the wavelength or wavelengths ofinterest after it hardens. Some imprint materials and stamping are wellknown in the art and may be selected at the discretion of theimplementer for the particular application.

In step 3707, an imprint stamp may be employed to shape the imprintmaterial to have a curved surface and a tilted flat surface suitable tobe used as a base for a curved mirror and a tilted flat mirrorrespectively. FIG. 40 shows an example imprint material 4013 in cavity3803 and also some example imprint material on top 3807 of SiPh chip3801 along with example imprint stamp 4015 such as may be used in step3707.

In step 3709, the imprint material may be hardened, such as, forexample, by curing, which may be through the use of, for example, acatalyst, e.g., ultraviolet (UV) light, heat, and so forth as well ascombinations of the forgoing, so as to retain the imprinted shape. Tothis end, if the catalyst employed is UV light, prior to exposing theimprint material to the UV light, mask 4016 of FIG. 40 may be employedto block UV light from reaching areas of SiPh chip 3801 on which theimprint material was deposited but which are not desired to be hardened.Mask 4016 should block the catalyst from reaching the imprint material,e.g., if the catalyst is UV light mask 4016 may be made of UV lightblocking metal, e.g., bronze, as is well known in the art. Mask 4016 maybe a part of imprint stamp 4015 or it may be separate therefrom andplaced on top of imprint stamp 4015. After hardening of the desiredportion of the imprint material, mask 4016 and imprint stamp 4015 may beremoved and any non-hardened imprint material, e.g., that which wasunder mask 4016 may be cleaned away.

FIG. 41 shows an example shaped and hardened imprint material 4013 withcurved surface 4117 and tilted flat surface 4119 following cleaning ofany possible non-hardened imprint material.

In step 3711, a reflective material, e.g., metal (e.g., chromium,silver, gold, copper, etc.), may be deposited over at least a portion ofcurved surface 4117 and a portion of tilted flat surface 4119. The metaldeposited may be selected so as to be substantially reflective to thewavelengths of light of interest and to thereby form curved mirror 4221and tilted flat mirror 4223 shown in FIG. 42 . For example, thewavelength of light may be in the 1200-1600 nm region, and the metalemployed may be gold, copper, chromium, etc. Those of ordinary skill inthe art will readily be able to select appropriate materials thatcorrespond to the particular wavelengths of interest. The curve ofimprint stamp 4015 that may be used to form curved surface 4117 mayconform to the desired shape of curved mirror 4221 and the portion ofimprint stamp 4015 that may be used to form tilted flat surface 4119 mayconform to the desired shape and tilt (e.g., angle) of tilted flatmirror 4223. In the description hereinbelow, curved mirror 4221 may bereferred to as first curved mirror 4221 and tilted flat mirror 4223 maybe referred to as first tilted flat mirror 4223.

In step 3713, electrical microbumps may be deposited on top 3807 of SiPhchip 3801. The electrical microbumps may be employed at least to coupleSiPh chip 3801 to a substrate when SiPh chip 3801 is flipped and placedagainst a substrate. The electrical microbumps may be a type of metal,e.g., solder, that may be placed on conductive pads, e.g., metallicpads, such as copper, or another conductive substance, on top 3807 ofSiPh chip 3801 and then reflowed if SiPh chip 3801 is flipped and placedon the substrate to which it is being mounted. FIG. 43 shows the examplestructure of FIG. 42 with example electrical microbumps 4325 placed ontop 3807 of SiPh chip 3801. Electrical microbumps 4325 may be highenough so that they may extend beyond top portion 4327 of the structureformed of hardened imprint material 4013. Additionally or alternatively,one or more of microbumps 4325 may consist of a downsized copper pillarand solder with height of, for example, around 30 m. The pads on whichmicrobumps 4325 may be placed are not shown but are well known in theart.

In step 3715, SiPh chip 3801 may be flipped and mounted to a substrate.The substrate may have additional devices, e.g., optical and/orelectrical devices (e.g., one or more ASICs), mounted thereon as well.According to one or more aspects, the substrate may be an interposerthat may be further mounted to a substrate (e.g., organic substrate, MCMsubstrate, etc.). SiPh chip may be attached to the substrate by, forexample, reflowing the microbumps. FIG. 44 shows SiPh chip 3801 flippedand mounted to substrate 4429 after reflow of solder microbumps 4325.According to one or more aspects herein, there may be conductive pads,e.g., metallic pads, such as copper, or another conductive substance, onthe substrate, e.g., substrate 4429. The pads of substrate 4429 are notshown but are well known in the art.

Substrate 4429 may be a multichip module (MCM) substrate that mayprovide for various electrical functions. For example, MCM substrate4429 may provide the base for multiple chips to be mounted thereon thatmay perform various electrical and/or optical functions. For example,one or more silicon photonics chips may be mounted on MCM substrate 4429although in FIG. 44 only SiPh chip 3801 is shown as a non-limitingexample. One or more electronic circuits, e.g., switches and/orapplication specific integrated circuits (ASICs), may also be mounted onMCM substrate 4429. MCM substrate 4429 may itself be mounted on a board(e.g., a PCB), not shown but well known in the art. As noted, thesubstrate may be an interposer that may then further coupled to an MCMsubstrate.

In step 3717, a photonic plug may be coupled to bottom 3809 of SiPh chip3801 with a spacer interposed between the photonic plug and bottom 3809.FIG. 45 shows photonic plug 4531 so coupled, and more specifically,photonic plug 4531 stacked on top of spacer 4533 which is on top ofbottom 3809 of SiPh chip 3801. Photonic plug 4531 may comprise secondcurved mirror 4535 and second tilted flat mirror 4537. Optical fiber4539 may be inserted into photonic plug 4531 so that light may becoupled between optical fiber 4539 and second tilted mirror 4537.Although only a single optical fiber 4539 is shown in FIG. 45 , it isexpected that generally there may be a plurality of fibers arranged inparallel in the photonic plug, as will be shown and described furtherhereinbelow. The optical fiber 4539 may be, for example, a single-modefiber (SMF).

As described herein, spacer 4533 may be glued, e.g., using an adhesive,to photonic plug 4531. Additionally or alternatively, spacer 4533 may beglued, e.g., using an adhesive, to SiPh chip 3801. Spacer 4533 may bemade of any transparent and non-conductive material, such as glass,polydimethylsiloxane, or any other index matching material.

The adhesive may have an appropriate index of refraction so as tominimize optical losses. For example, if optical fiber 4539 and spacer4533 are each made from fused silica that has an index of refractionaround 1.5, in order to minimize optical losses, the index of refractionof the adhesive may be around 1.5 as well. Those of ordinary skill inthe art will readily be able to select an adhesive having an appropriateindex of refraction based on the materials employed in their variousapplications. Spacer 4533 may be optically transparent to at least onewavelength of light being carried by optical fiber 113 and employed bySiPh chip 3801. Spacer 4533 may be made of any transparent andnon-conductive material, such as glass, polydimethylsiloxane, or anyother encapsulation material with appropriate refractive index.

Spacer 4533 may be used, at least in part, to control (e.g., set) thedistance between photonic plug 4531 and SiPh chip 3801 so as to enablethe proper optical operation of the system. Spacer 4533 may also be usedto at least partially encapsulate and help hold in place optical fiber4539. To this end, adhesive may be employed between at least a portionof spacer 4533 and at least a portion of photonic plug 4531 to keepspacer 4533 attached to photonic plug 4531.

At least one of first curved mirror 4221 and second curved mirror 4535may be structured and configured to reflect substantially allwavelengths of light incident thereupon.

FIG. 46 shows a portion of an example surface 4671 usable for photonicplug 4531 in which second curved mirrors 4535 and tilted flat mirrors4537 may be formed, each corresponding set of a one of curved mirror4535 and a one of tilted flat mirrors 4537 being for a respective one ofoptical fibers 4539. Also, shown in FIG. 46 are trenches 4641, (e.g.,retaining features/alignment features described herein) e.g., V-grooves,for guiding optical fibers 4539, retaining optical fiber, and/oraligning optical fibers (e.g., in the X, Y and/or Z directions). FIG. 46shows four fiber trenches 4641-1 through 4641-4. Each fiber trench 4641adjoining a corresponding one of second tilted flat mirrors 4537, e.g.,second tilted flat mirrors 4537-1 through second tilted flat mirrors4537-4. According to the example depicted in FIG. 46 , each of fibertrenches 4641 are shaped as V-grooves formed in a substrate layer ofphotonic plug 4531 (alternative alignment features, as described herein,are contemplated). Each of fiber trenches 4641 may be formed, forexample, by etching. Each of second tilted flat mirrors 4537-1 through4537-4 may be oriented so as to be able to direct light between opticalfiber 4539 and a corresponding respective first curved mirror 4221formed on Si Ph chip 3801. FIG. 46 also shows four second curved mirrors4535-1 through 4535-4. Each of second curved mirrors 4535 may beoriented so that if photonic plug 4531 is coupled to spacer 4533 whichis in turn coupled to bottom 3809 of SiPh chip 3801, the interior ofeach of second curved mirror 4535 may be facing toward bottom 3809 ofSiPh chip 3801.

It should be noted that only 2 optical fibers 4539-1 and 4539-2 and fourfiber trenches 4641 are shown in FIG. 46 for example purposes only.Other numbers of optical fibers and trenches may be used withoutdeparting from the scope of the present disclosure. It should be furthernoted that trenches 4641 are described as V-grooves. However, any typeof groove shape can be used, such as square, cylinder, diamond, and thelike.

FIG. 46 shows optical fibers 4539-1 and 4539-2 placed in the fibertrenches 4641-1 and 4641-2, respectively. According to one or moreaspects, the height of at least one of fiber trenches 4641 may besubstantially the same as the diameter of a one of optical fibers 4539that is placed therein. Doing so with all of fibers 4539 may enablespacer 4533 to have a flat surface that may be flush against photonicplug 4531. Alternatively, spacer 4533 may be shaped so as to accommodateother heights for fiber trenches 4641. Second tilted flat mirrors 4537and second curved mirrors 4535 may be positioned to provide for a properoptical path with respect to the depth and orientation of fiber trenches4641. The depths of trenches 4641 shown in FIG. 46 and the diameter offibers 4539 shown in FIG. 46 are simply for pedagogical purposes to makeit easy to facilitate explanation of the concept and do not reflect anyparticular preferred or real-world depth, diameter, or optical path.

Processes for creating a fiber trench may be well known in the art.Adhesive may also be placed within trenches 4641 or around opticalfibers 4539 to secure optical fibers 4539 with photonic plug 4531.

According to one or more aspects herein and referring to FIG. 42 ,tilted flat mirror 4223 may be replaced by a tilted curved mirror (TCM).Such a titled curved mirror may act as and/or be configured similarly toa focusing element that can change the mode size of the light beam. Forexample, the tilted flat mirror may be used in an example configurationwhere the mode diameter of the waveguide is, for example, 9 um.Additionally, when the waveguide mode field diameter is different than 9um the titled curved mirror may be employed as well. The tilted curvedmirror may be shaped and oriented so that not only does it change thedirection of the light, similar in this regard to titled flat mirror4223 (and first turning mirrors herein, e.g., first turning mirror 120),but due to its curvature it may also converts the light's mode size.Such a tilted curved mirror may be formed by imprint stamping in thesame manner as described above for tilted flat mirror 4223 and curvedmirror 4221 but using an imprint stamp that may be shaped so as to forma tilted curved mirror surface in lieu of tilted flat surface 4119.

Additionally or alternatively, tilted flat mirror 4223 may be employedand mode conversion may be achieved by forming of the imprint material amode converter between the end of waveguide 3805 and tilted flat mirror4223. The mode converter may be made of an inverted taper and a lineartaper (e.g., as described with respect to FIGS. 18A-18C) which may beformed of the imprint material at the same time as the formation curvedsurface 4117 and tilted flat surface 4119 takes place, e.g., as part ofthe same steps that are used to form curved surface 4117 and tilted flatsurface 4119, by using an appropriately shape imprint stamp.

Additionally or alternatively, if a grating coupler has beenincorporated into SiPh chip at the end of waveguide 3805, the gratingcoupler redirecting light between waveguide 3805 and second curvedmirror 4535, tilted flat mirror 4223 may not be formed at all.

Additionally or alternatively, the imprinted structure could be formedas a separate part, e.g., formed on glass or other substrate that may betransparent to light at the wavelength of interest, and then installed,e.g., adhered, onto the SiPh chip, e.g., so as to extend at least partlywithin a cavity formed therein as disclosed above.

As may be appreciated, detachability of optical connectors may proveadvantageous according to some uses and/or configurations. Accordingly,aspects of the present disclosure relate to detachable connectors (e.g.,optical couplers).

FIG. 47 shows an example of a fully assembled detachable connector forco-packaged optics coupled to a multi-chip module via a PIC. Shown inFIG. 47 are a) MCM substrate 4701, b) PIC 4705, c) receptacle 4707, d)detachable plug die 4709, e) removable clip 4711, f) optical fibers 4713arranged into fiber ribbons 4713-1 and 4713-2, and g) fiber ribbonconnector couplers 4715-1 and 4715-2.

FIG. 48 shows an exploded view of the example that is shown in FIG. 47 .

MCM substrate 4701 may provide for various electrical functions. MCMsubstrate 4701 may provide the base for multiple chips mounted thereonthat may perform various electrical and optical functions. For example,one or more photonic integrated circuits (PICs) 4705, may be mounted onMCM substrate 4701 although in FIGS. 1 and 2 only a single PIC is shownas a non-limiting example any number of PICs may be mounted on MCMsubstrate 4701. One or more electronic circuits, e.g., switches andapplication specific integrated circuits (ASICs), may also be mounted onMCM substrate 4701. MCM substrate 4701 may itself be mounted on a board(e.g., a PCB) (not shown in FIG. 1 or 2 ). PIC 4705 may be reflowsoldered to MCM substrate 4701.

Receptacle 4707 may be reflow soldered or glued, e.g., using anadhesive, to PIC 4705, MCM substrate 4701 or a combination thereof. Thismay be performed, advantageously, using a standard pick and placemachine and as such, advantageously, it can be placed with highaccuracy. It may be placed during the packaging process, e.g., duringthe placing of one or more chips, e.g., one or more ASICs on the MCMsubstrate 4701.

FIG. 49 shows another view of example detachable plug die 4709 insertedinto example receptacle 4707. FIG. 50 shows an exploded view of theexample of FIG. 49 but without optical fibers 4713.

Detachable plug die 4709 is described further hereinbelow. Detachableplug die 4709 may be detachable due to its ability to be inserted intoand correspondingly removed from receptacle 4707.

Removable clip 4711 may extend over the top of receptacle 4707 and maypress down on detachable plug die 4709 in order to keep the componentsin place. The removable clip 4711 may extend over the top and around twoopposing sides of receptacle 4707 which it may grip to stay in position.Receptacle 4707 may have one or more indentations (not shown) to aidclip 4711 to remain in place. Clip 4711 may be retained in place byfriction. Additionally or alternatively, clip 4711 may be attached toPIC 4705 and/or MCM substrate 4701. After being placed, removable clipmay be removed to allow detachable plug die 4709 and fibers 4713 to beseparated from PIC 4705. Although depicted in examples herein as beingfully detachable, those of ordinary skill in the art will readilyrecognize that at least one end of clip 4711 may be arranged to bepermanently attached to receptacle 4707 and may be openable, e.g., usinga hinge mechanism.

Detachable plug die 4709, spacer 4721, and fiber 4713 taken together maybe considered to be a detachable photonic plug that can be used toconnect optical signals between PIC 4705 and the fibers to which fiberribbon connector couplers 4715 are connected. The components of thedetachable photonic plug, including detachable plug die 4709, fibers4713, and spacer 4721 may be assembled, e.g., as shown in FIG. 51 ,prior to being inserted into receptacle 4707.

Spacer 4721 may be used at least in part to control the distance betweendetachable plug die 4709 and PIC 4705 so as to enable the proper opticaldesign of the system (e.g., to effectively space mirrors of the systemand/or apparatus). Spacer 4721 may also be used to at least partiallyencapsulate and help hold in place fibers 4713. To this end an adhesivemay be employed between at least a portion of glass spacer 4721 and atleast a portion of plug die 4709 to keep spacer 4721 attached to plugdie 4709. Adhesive may also be placed within the trenches or aroundoptical fibers 4713.

It may be advantageous for the adhesive to have an appropriate index ofrefraction so as to minimize optical losses. For example, when opticalfibers 4713 and spacer 4721 is made from fused silica that may have anindex of refraction around 1.4, in order to minimize optical losses, theindex of refraction of the adhesive may be around 1.4 as well. Those ofordinary skill in the art will readily be able to select an adhesivehaving an appropriate index of refraction based on the materialsemployed in their various applications. Spacer 4721 may be opticallytransparent to at least one wavelength of light being carried by opticalfibers 4713 and employed by PIC 4705. Spacer 4721 may be made of anytransparent and non-conductive material, such as glass,polydimethylsiloxane, or any other encapsulation material withappropriate refractive index.

Initial insertion of the detachable photonic plug, by initial insertionof detachable plug die 4709 thereof, into receptacle 4707 may provide arough positioning tolerance of +/−100 μm as a first step before finealignment. In other words, receptacle 4707 may position detachable plugdie 4709 between −100 μm to +100 μm on both the x and y axis, where 0 μmis the ideal position. If detachable plug die 4709 is fully pressed intoreceptacle 4707, fine alignment male features 117, e.g., small maleprotrusions, of detachable plug die 4709, e.g., as seen in FIG. 50 ,connect to corresponding fine alignment female features 119 of PIC 4705,e.g., small recesses, e.g., as seen in FIG. 50 , that match the size andshape of fine alignment male features 117, which may provide +/−5 m orbetter fine positioning tolerance for the location of detachable plugdie 4709. Each of fine alignment male features 117 and fine alignmentfemale features 119 may be produced by wafer level manufacturingprocesses on both PIC 4705 and the detachable plug die 4709.Advantageously, such a mechanical structure where the alignment isperformed using such alignment features produced at the wafer level mayprovide for superior control of the alignment.

According to one or more aspects fine alignment features may beincorporated into spacer 4721 in addition to or in lieu of those ofdetachable plug die 4709. Additionally or alternatively, detachable plugdie 4709 may comprise alignment features to help insure proper placementof spacer 4721.

FIG. 52 shows a cross sectional view of an example detachable connectorif assembled and an example optical path. However, a difference betweenthe FIG. 52 and that of FIG. 50 is that in FIG. 52 detachable plug die5209 has female fine alignment features 5219 instead of male finealignment features 119 while PIC 5205 has male fine alignment features5217 instead of male fine alignment feature 117. However, from the pointof view of light traversing from fiber 4713 to PIC 5205 via detachableplug die 5209, the same or similar path may be undertaken if using PIC4705 and detachable plug die 4709.

The optical path may comprise, in part, a plurality of mirrors, and inparticular, first curved mirror 4723, second curved mirror 4725 andtilted flat mirror 4727. Tilted flat mirror 4727 may be used to direct alight beam from optical fiber 4713 to first curved mirror 4723 andvice-versa. This optical fiber 4713 may be held in an orientation withrespect to PIC 5205 so as to ensure that light from PIC 5205 goes intooptical fiber 4713 and vice-versa. Tilted flat mirror 4727 may be formedby being etched using a CMOS etching process or in an imprint process.The particular angle employed may be based on the optical path betweenoptical fiber 4713 and first curved mirror 4723 and may be selected sothat light from tilted flat mirror 4727 may be reflected tosubstantially the center of first curved mirror 4723.

First and second curved mirrors 4723 and 4725 may be placed so thattheir respective reflective curved surfaces face in opposite directionsto each other. Specifically, first curved mirror 4723 may be within on,and/or proximate to PIC 5205 with its curved reflective surface facinggenerally toward detachable plug die 5209 while second curved mirror4725 may be within, on and/or proximate to detachable plug die 5209 withits curved reflective surface facing generally toward PIC 5205. As aresult of the arrangement of the mirrors, light from fiber 4713ultimately is directed into waveguide of PIC 4705 and vice-versa,depending on the application. Advantageously, the arrangement of theoptical components may allow for separation of optical fiber 4713 fromPIC 5205 which may facilitate detachability while still providing highand relaxed alignment tolerances in three-dimensions for the coupling offibers 4713 using the detachable photonic plug. In addition, furtheradvantageously, of the optical components may enable placement of thedetachable plug as a one unit relative to the PIC.

According to one or more aspects herein, first and second first curvedmirrors 4723 and 4725 may be created using a process such as, but notlimited to, grayscale lithography or wafer level optics imprinttechniques. Tilted flat mirror 4727, second curved mirror 4725, and thefiber trenches may be formed using the same wafer level manufacturingprocess with high alignment accuracy or other processes as describedherein.

Further, each of first and second first curved mirrors 4723 and 4725 maybe created during fabrication of PIC 5205 and detachable plug die 5209,respectively, which may ensure high accuracy positioning and accuratereflective mirrors. As a non-limiting example, the fabrication processused to create first curved mirrors 4723 and 4725 and tilted flat mirror4727 may comprise a Silicon-On-Insulator (SOI), complementarymetal-oxide semiconductor (CMOS), wafer level optics based imprintprocesses, and the like.

The disclosed arrangement of the optical coupler may achieve high signalefficiency with a relaxed alignment between PIC 5205 and the detachablephotonic plug as a unit due to the specific locations, shape, andorientation of first and second first curved mirrors 4723 and 4725.Specifically, first and second first curved mirrors 4723 and 4725 may beshaped in such a way that a light beam from a source, which may be oneof fibers 4713, may be reflected and collimated at a certain anglesubstantially at a center of first curved mirror 4723 and focused to adrain, e.g., waveguide 4729 of PIC 5205, after second curved mirror4725. Likewise, first and second first curved mirrors 4723 and 4725 mayalso be shaped in such a way that any light beam from a source, e.g.,waveguide 4729 of PIC 5205, may be reflected and collimated at a certainangle substantially at a center of second curved mirror 4725 and focusedto a drain, e.g., which may be one of fibers 4713, after being reflectedby first curved mirror 4723 via tilted flat mirror 4727.

More specifically, as shown in FIG. 52 , a light beam 4731 that wasreceived from optical fiber 4713 may be reflected by tilted flat mirror4727 as diverging light beam 4733 toward first curved mirror 4723. Lightbeam 4733 may be reflected by first curved mirror 4723 as light beam4735 and reach second curved mirror 4725. Second curved mirror 4725 inturn may reflect light beam 4735 as focused light beam 4739 to backvertical to horizontal propagation converter 4737 (e.g., PIC I/Ointerface, e.g., TCM, TCM photonic bump, turning mirror, taperedwaveguide photonic bump, and/or grating coupler). Vertical to horizontalpropagation converter 4737 may convert received focused light beam 4733to a horizontal propagation for light insertion into waveguide 4729 ofPIC 5205. The optical path may be the same but in reverse for a lightbeam transmitted by the waveguide 4729.

Vertical to horizontal propagation converter 4737 may be a gratingcoupler. Additionally or alternatively, a tilted-curved mirror orpositive tapered structure may be employed individually or incombination as vertical to horizontal propagation converter 4737.Further, vertical to horizontal propagation converter 4737 may be a buttwaveguide coupler, e.g., an out-of-plane butt coupler. Vertical tohorizontal propagation converter 4737 may also have additionalcomponents that allow it to function as a mode converter in order toadapt the light between the mode size of, for example, waveguide 4729and the single mode fiber mode diameter if fiber 4713 is a single modefiber.

According to one or more aspects herein, first curved mirror 4723 andvertical to horizontal propagation converter 4737 may be referred to aspart of a so-called “photonic bump” which may be added to PIC 4705 in awafer level process or one or more other processes. These components maybe fabricated at the same wafer level process to guarantee highalignment accuracy. However, note that such a bump need not bemanufactured at the same time that PIC 4705 is manufactured. Therefore,such a photonic bump can be added by another party, e.g., a party whodid not manufacture the rest of PIC 4705.

Spacer 4721 may be glued, e.g., using an adhesive, to detachable plugdie 5209 as described above with regard to detachable plug die 4709.According to one or more aspects, additional spacer portion 5261 may beglued, e.g., using an adhesive, to PIC 5205. Additional spacer portion5261 may be made of, for example, any transparent and nonconductivematerial, such as glass, polydimethylsiloxane, or any other indexmatching material. While the alignment features are shown in FIG. 52 asbeing on the PIC, they may, additionally or alternatively, be made onadditional spacer portion 5261 or a combination thereof.

Fine alignment features may be incorporated into additional spacerportion 5261 in addition to or in lieu of those of PIC 4705.Additionally or alternatively, PIC 4705 may comprise alignment featuresto help insure proper placement of additional spacer portion 5261.

Due to the detachability of plug die 4709 from PIC 4705, there may be agap, e.g., air gap 5263, between spacer 4721 and additional spacerportion 5261. Such a gap may cause mismatches and/or scattering at theboundaries with spacer 4721 and additional spacer portion 5261 resultingin signal loss. To ameliorate such loss, a layer of antireflectivecoating may be applied to one or more portions of one or both of thesurfaces of spacer 4721 and additional spacer portion. Morespecifically, an antireflective coating layer may be applied to at leasta portion of the surface of spacer 4721 that faces PIC 5205.Additionally or alternatively, an antireflective coating layer may beapplied to at least a portion of the surface of additional spacerportion 5261 that may face detachable plug die 5209. Such antireflectivecoating may be a dielectric material and may, for example, be a layer ofmagnesium fluoride, although those of ordinary skill in the art will beable to select an antireflective coating suitable to the materials andgap employed. Advantageously, the antireflective coating layers maysubstantially overcome the difference, e.g., a mismatch, in the index ofrefraction as light propagates from one medium to another.

The total spacing height between PIC 5205 and plug die 5209, and inparticular the height between the mirrors, which may be determined bythe total height of spacer 4721 which may comprise any antireflectivecoating if present, spacer portion 5261 which may comprise anyantireflective coating if present, and any gap between them, e.g., gap5263, determines, in part, the efficiency of the transference of a lightbeam, e.g., optical signal, that is propagating along the optical path.Specifically, the greater the total height is, the less the efficientthe transference may be. Those of ordinary skill in the art will readilybe able to determine an appropriate height for the total spacing andeach of its component elements. In an exemplary and non-limitingexample, the total height may be set to 300-μm.

Although the optical path was described regarding a connection between asingle fiber and PIC 5205, it will be clear to those of ordinary skillin that the example path may be applied to a plurality of fibers, e.g.,all fibers 4713 in fiber ribbon 4713 as well as any other opticalcomponents (e.g., lasers, waveguides, etc.).

Also shown in FIG. 52 is MCM substrate 4701 to which PIC 5205 may beattached by microbumps 4761. Microbumps 4761 may each be a ball ofsolder that may provide contact between PIC 5205 package and MCMsubstrate 4701. One or more of microbumps 4761 may consist of adownsized copper pillar and solder with, for example, height of lessthan 20 m. Microbumps 4761 may electronically connect MCM substrate 4701and PIC 5205. Microbumps 4761 may connect copper pads on MCM substrate4701 and PIC 5205 and soldering may be performed by reflow soldering.

FIG. 52 further shows the section of example receptacle 4707 that isvisible in the view of FIG. 52

Detachable plug die 4709 may have trenches, e.g., V-grooves, to holdeach corresponding fiber 4713 so as to properly space and distance themas described herein.

As discussed above, aspects of the present disclosure relate to ascalable fiber to chip assembling and/or packaging methodology inapplications where, for example, fiber high density or large port countis desired, for example, co-packaged optical Switch connectivity (forexample, the configuration as depicted in FIG. 19 ). Co-packaged opticalconnectivity brings multiple fibers closer to Switch die which may bepackaged on an expensive packaging platform such as a Multi-Chip Module(MCM). Therefore, if may be advantageous for co-packaged opticalconnectivity to be compatible with standard chip packaging methodologiesand equipment. Separating the fiber from the MCM packaging steps, andkeeping the fiber and MCM packaging to the last stage in a pluggable wayis not only unique, but also makes the process a scalable technology.

Furthermore, fiberless detachable connections are suitable not only inswitches, but also in transceivers and other applications such asconnections between memory and processors and chip-to-chip connectivityin general.

An electro-optical interconnection platform for co-packaging ahigh-speed switch to high-density optical engine is disclosed. Theplatform may comprise a fiberless optical coupler that may cover variousgeometries. The coupler may comprise a plurality of mirrors, one or moremechanical aligners for fiber mount connector, for example, rods locatedin V-grooves, which may be accurately placed relative to the optics, anda waveguide (e.g., a polymeric waveguide or other types of mirror withdifferent optical arrangements). In an example, the chip may comprise aplurality of mirrors, and a positive tapered waveguide, an interfacemedium, (e.g., MCM), and a high-speed switch die. In an additional oralternative example, a laser can be part of the platform.

Additionally aspects of the present disclosure relate to a fiberlessoptical coupler for interfacing with an optical fiber connector and aPhotonic Integrated Circuit (PIC). The coupler may comprise a pluralityof mirrors, one or more mechanical alignment features, and a waveguide,(e.g., a polymeric or Si waveguide).

FIG. 53 is a top view of an example electro-optical interconnectionplatform 5300 according to the present disclosure. The example platform5300 may comprise one or more of a fiberless optical coupler 5301 (alsoknown as fiberless Photonic Plug (PhotonicPlug) coupler), an IntegratedCircuit (IC) 5305, and a laser source 5316 packaged on a PIC 5302 (alsoknown as a photonic chip or high-density optical engine), and ahigh-speed switch die 5304 co-packaged with the PIC 5302 as a set ofelectronic components on an MCM 5303.

The fiberless optical coupler 5301 may be designed and/or configuredwith an optical arrangement that may provide high tolerance alignmentand a passive positioning of the fiberless optical coupler, thus, forexample, aligning the optical fiber with respect to the PIC. Thefiberless optical coupler 5301 may be similar to, and/or comprise,and/or be comprised by the optical couplers of, for example, one or moreof the optical couplers described herein (for example, with reference toFIGS. 1-18C. The fiberless optical coupler 5301 can be mass-produced andits design may further allow for compact and secured packaging of PICs.

One or Multiple sets of the fiberless optical coupler 5301, the PIC5302, the IC 5305 and the laser source 5316 may be assembled surroundingthe high-speed switch die 5304 on the MCM 5303.

Each of the fiberless optical coupler 5301 may be connected toelectrical-optical connectors 5320 and the fiber array 5330 to transmitpower or data to the components mounted on the MCM 5303, the details ofwhich will be further discussed below. Also, the fiberless opticalcoupler 5301 may be assembled on the PIC 5302 through a flip-chipmachine (not shown) and/or process with passive alignment and largetolerances using “self-aligning optics” as described herein. Suchalignment may not require additional adjustments or alignment of theoptical components, and accurate placement of mechanical aligners withreference to optics at wafer level sizes may be enabled.

It should be appreciated that by using a flip-chip machine and/orprocess, and using the self-aligning optics, surface coupling may beachieved, and issues with complicated edge geometry (e.g., associatedwith edge coupling of optical fiber to PIC) may be relieved.

FIG. 54 is an example magnified view of the example electro-opticalinterconnection platform 5300 according to present disclosure. Thefiberless optical coupler 5301 may comprise a mechanical aligner 5401that may be compatible with various types of electrical opticalconnectors 5320 that may ensure mechanical alignment of, for example, afiber ribbon relative to the optics on the fiberless optical coupler5301.

According to further aspects, the mechanical aligner 5401 may be a pairof cylindrical rods arranged on opposite sides of the fiberless opticalcoupler 5301 at a distal end, both of which may be connectible to theelectrical optical connectors 5320. The pair of cylindrical rods may besubstantially parallel to each other and may be of a similar length. Theassembly of the electro-optical interconnection platform 5300 can beperformed by, for example, connecting the fiberless optical coupler 5301on the MCM module 5303 to a switch board (not shown).

FIG. 55 is an example schematic side view of the example electro-opticalinterconnection platform 5300 according to the present disclosure. Thefiberless optical coupler 5301, which may also be referred to as anoptical die and may also comprise the mechanical aligner 5401, may bemounted on the PIC 5302 adjacent to the IC 5305, which may also bereferred to as the switch IC die. The PIC 5302 may in turn be mounted onthe MCM module 5303, and the entire assembly including the fiberlessoptical coupler 5301, the mechanical aligner 5401, IC 5305, PIC 5302,and the MCM module 5303 may be mounted on (e.g., packaged with) aprinted circuit board (PCB) 5501.

As shown in the example FIG. 55 , the co-packaged components may reducepower consumption, as this arrangement brings the components closer tothe IC 5305, thereby reducing the electrical port's length to, in anexample, about 2-3 millimeters, compared to the 10-15 centimeterselectrical link seen in typical pluggable transceiver opticsconnectivity. According to aspects, herein, any electrical port lengthis contemplated herein (e.g., where additional length is desired forphysical configuration considerations).

FIG. 56 is an example diagram of a high magnification of the examplefiberless optical coupler 5301 according to one or more aspects of thepresent disclosure. The mechanical aligner 5401, illustrativelydescribed as a pair of mechanical alignment rods may be included on thefiberless optical coupler 5301. The fiberless optical coupler 5301 mayalso comprise wafer-level optical elements 5610, for example opticalelements as described herein. Based on the description below, theseoptical elements 5610 may be “self-aligning.”

According to one or more aspects herein, the optical elements 5610 maycomprise a plurality of waveguides 5613-1 through 5613-n (collectivelyreferred to as a waveguide 5613 or waveguides), deflectors 5615-1through 5615-n (collectively referred to as a deflector 5615 ordeflectors 5615) and curved mirrors 5617-1 through 5617-n (collectivelyreferred to as a curved mirror 5617 or curved mirrors 5617). The opticalelements 5610 may be arranged between the mechanical alignment rodswithin the fiberless optical coupler 5301, and may be arranged to guidelight waves to and from the fiber array (not shown) and elements, thedetails of which will be further described in FIG. 57 .

It is noted that other types of mechanisms besides mechanical alignmentrods may be used to ensure alignment. An example of such an alternativearrangements will be discussed with respect to FIG. 59 .

FIG. 57 is a schematic side view of an example fiberless optical coupler5301 on the PIC 5302 according to the present disclosure. The fiberlessoptical coupler 5301 may comprise the optical elements 5610, which maycomprise the waveguide 5613, the deflector 5615 (e.g., first turningmirror), and the curved mirror 5617.

The waveguide 5613 may be a polymeric or a silicon (Si) waveguide. Ifpolymer is used for the waveguide 5613, the polymer may be designed tomatch the single-mode fiber optics in terms of mode diameter. Also, thedeflector 5615 may be a reflective surface, for example a tiltedreflective surface.

The PIC 5302 may comprise a second plurality of optical elements 5710for coupling with the wafer-level optics elements 5610 of the fiberlessoptical coupler 5301. The second plurality of optical elements 5710 maycomprise a curved mirror 5713, a deflector 5715, and a tapered polymerwaveguide 5715. It will be appreciated that the deflector 5715 andtapered polymer waveguide 5715 may be replaced by alternativecomponents, for example, a TCM or one or more elements of a photonicbump as described herein. The PIC 5302 may also comprise an additionalpolymeric or a silicon waveguide 5719 (e.g., PIC I/O waveguide).

Additionally, a spacer 5720 may be included in between the fiberlessoptical coupler 5301 and the PIC 5302, for light from the waveguides5401, 5715 to travel through after being reflected by the correspondingdeflectors 5615, 5715 and curved mirrors 5617, 5713. The spacer 5720 maybe made of a transparent and non-conductive material, such as glass,polydimethylsiloxane, air, or any other index matching materials.Additionally or alternatively, the spacer may be a material that is nottransparent to visible light but substantially transparent to thewavelength of the light beam (e.g., infrared), for example, asilicon-based material. The height of the spacer 5720 may determine, inpart, the efficiency of the light beam (optical signal) that propagatesthrough the spacer 5720. In one example, the height of the spacer 5720may be about 300 microns, though other heights are contemplated herein.

FIG. 58 is a schematic side view of the example fiberless opticalcoupler 5301 on the PIC that is attached to the fiber array 5330,according to one or more aspects of the present disclosure. Here, thevarious components of the fiberless optical coupler 5301, PIC, 5302, andthe spacer 5720 are substantially the same as that shown in FIG. 57 .The fiberless optical coupler 5301 may be coupled to the opticalconnector 5320 via the mechanical aligner 5401, which may house the endtips of the fiber array 5330.

The mechanical aligner 5401 may be arranged so that if the aligner 5401is inserted into the optical connector 5320, the fiber array 5330 may beaccurately aligned to the polymeric waveguide 5613 with the same beammode size within the fiberless optical coupler 5301, with a spacedefined by the length of the mechanical aligner 5401 in between thefiberless optical coupler 5301 and the optical connector 5320.

As described herein, according to one or more aspects, the positioningof the mirrors 5617, 5713, and the deflectors, 5615, 5715 can beperformed using a wafer level process such as, but not limited to,grayscale lithography or other processes described herein. The mirrors5617 and 5713, may be placed and created during fabrication, which mayensure high accuracy positioning and accurate reflective mirrors. Forexample, the curved mirror 5617, deflector 5615, and waveguide 5613 mayall be placed by wafer level process with high accuracy. Alternatively,as described herein, the elements may be added at the same or later timeto the time of fabrication by one or more of various processes. On thePIC 5302 side, waveguide 5715, deflector 5715, and curved mirror 5713may similarly be placed.

As a non-limiting example, the fabrication process used to create themirrors may comprise wafer level imprint lithography, and may comprisethe use of a Silicon-On-Insulator (SOI), and Complementary Metal-OxideSemiconductor (CMOS).

FIG. 59 is a schematic side view of an example electro-opticalinterconnection platform 5300 according to one or more aspects of thepresent disclosure. An MCM 5303 is shown along with the PIC 5302including an SOI wafer 56020 mounted on a socket 5930, the socket 5930being coupled to the MCM 5303. The fiberless optical coupler 5301 may belocated on the PIC 5302, with the fiberless optical coupler 5301 coupledto the fiber array 5330. The fiberless optical coupler 5301 may comprisea first set of optical elements 5610, and the SOI wafer 56020 maycomprise a second set of optical elements 5710. Each of the first andsecond sets of the optical elements 5610, 450 may have similarcomponents as described in FIGS. 4 and 5 and 1-18C.

The mechanical aligner 5401 previously described in FIG. 53 may beconfigured as a Mechanical Optical Device (MOD) 5940 located between thefiberless optical coupler 5301 and the PIC 5302. The first set ofoptical elements 5610 and the second set of optical elements 5710 may bealigned with the fiber array 5330, via the MOD 5940, in order for lightto transmit in between the fiber array 5330 and the PIC 5302 through thesets of the optical elements 5610, 5710.

The MOD 5940 may allow light to pass through between the sets of theoptical elements 5610, 5710 within the fiberless optical coupler 5301and the PIC 5302. Also, the MOD 5940 may further comprise V-shapedgrooves 5950 that may receive the fiberless optical coupler 5301, sothat the optical elements 5610, 5710 may be in alignment with the fiberarray 5330 when receiving light transmitted to and from the fiber array5330. That is, the V-shaped grooves 5950 may ensure a later alignedplacement of additional optical elements 5610 included in the fiberlessoptical coupler 5301.

FIG. 60 is an example method of manufacturing an electro-opticalinterconnection platform 5300, according to one or more aspects of thepresent disclosure. At S6010, the PIC 5302 may be formed, in which thelaser source 5316 may also be formed on the PIC 5302. Next, at 56020,the second optical elements 5710 may be formed on the PIC 5302, whilethe optical elements 5610 may be separately formed on the fiberlessoptical coupler 5301. Further, at S6040, a mechanical aligner 5401 maybe formed.

Additionally, at S6040, the PIC 5302 may be coupled on the MCM 5303, andat S6050, the MCM 5303 may be coupled on the PCB 5501. Next, at S6060,the fiberless optical coupler 5301 may be coupled to the PIC 5302, andat S6070, the fiberless optical coupler 5301 may be coupled to the fiberarray 5330.

With the method 6000 above, a flip-chip assembly process may be used toemployed to couple components of the PIC 5302 together (e.g., couplingSOI wafer with the socket) and with other elements, and coupling themechanical aligner 5401 to the PIC 5302 or the fiberless optical coupler5301. This may ensure accurate placement of the optics on the PIC 5302.Also, if the MOD 5940 is used, additional accuracy in aligning opticalelements 5610, 5710, along with added optical functionality of the MOD5940 may be achieved.

FIG. 61 is a schematic side view of an example electro-opticalinterconnection platform 5300 according to the present disclosure. Here,the components of the platform 5300 may be arranged in substantially thesame way as depicted in FIG. 59 . However, the optical elements 5710that were previously located within the PIC 5302 may instead be formedwithin the MOD 5940. By having the optical elements 5710 formed in theMOD 5940, further alignment of the optical components may be assured,and the MOD 5940 may be given additional optical functionality besidesbeing just a medium or spacer that provides merely mechanical alignmentbetween the various optical elements 5610, 5710 and the fiber array5330.

It may be appreciated that lasers are often used in the communicationchain in optical and electro-optical systems. As disclosed herein, it iscontemplated herein the optical couplers of the present disclosure mayvariously couple lasers as an optical component (e.g., optical sourceand/or drain). Accordingly, advantages of the present disclosure (e.g.,“self-aligning optics”) may be used with lasers. Lasers may be usedvariously in optical and electro-optical systems. For example, lasersmay be on-chip or off-chip. On-chip lasers may refer to a laser die thatis directly integrated with (e.g., connected) to a SiPh chip (e.g., aPIC). Where lasers are on-chip, the couplers of the present disclosuremay be used substantially as described. For example, the on-chip lasermay be a part of any of the PIC I/O interfaces and/or connected toand/or instead of a PIC I/O waveguide.

The optical couplers of the present disclosure may also proveadvantageous for coupling off-chip lasers to other optical components(e.g., PIC, chips, optical fibers, etc.). FIG. 62 shows an exampleco-packaged optics with a plurality of laser modules. The package ofFIG. 62 may be similar to and/or comprise and/or be comprised by thepackages of, for example, FIGS. 19 and/or 53 . The package may comprisean MCM substrate 6203. One or more chiplets 6205 (e.g., optical engines)may be packaged with (e.g., on) MCM substrate 6203. Chiplets 6205 may beelectrically and/or optically packaged with MCM substrate, and thepackaged chiplets 6205 may be electrically and/or optically connected toeach other via MCM substrate 6203. Each chiplet 6205 may comprise a SiPhchip 6207 (e.g. PIC) for optical connection and/or communication to offpackage components. According to the example of FIG. 62 , optical fiberribbon 6213 may be connected to each SiPh chip 6207 for opticalcommunication to and from the SiPh chip 6207. Each optical fiber andfiber ribbon 6213 may be connected to the SiPh chip via an opticalcoupler 6201A of the present disclosure (e.g., having a photonic pluglayer, spacer, first and second curved mirror, turning mirror, etc.).

In addition, the package may comprise off-chip laser modules 6215. Oneor more of the chiplets 6205 and/or SiPh chips 6207 may be connected toa laser module 6215. Laser module 6215 may be used for communication inthe electro-optical package.

FIG. 63 depicts an example laser module 6215 according to one or moreaspects of the present disclosure. Referring to FIG. 63 , each lasermodule 6215 may comprise a substrate 6303 which may be referred toherein as a socket. The substrate 6303 may be host one or more carriers6305 which may be packaged with the substrate 6303. Each carrier 6305may comprise one laser 6377 or an array of lasers 6377. The lasers 6377may be, for example, diced from a laser wafer. Each laser array and/orcarrier may have an associated IC 6309 for controlling and/orcommunicating with the carrier 6305 or other carriers 6305. The Lasers6377 may be connected to other optical components via optical connector6300. The optical connector 6300 may comprise optical elements asdescribed herein, and described below in more detail.

FIG. 64 show an example laser coupled to a fiber utilizing one or moreaspects of an example optical coupler of the present disclosure.Referring to FIG. 64 , the laser may be packaged with the carrier 6305.The carrier 6305 may be, for example a silicon substrate. The laser 6377chip and/or the carrier 6305 may comprise alignment features 6482A and6482B, to align the laser 6377 die on the carrier 6305. Additionally,electrical connection features 6462 (e.g., solder bumps) may be includedbetween the laser die 6307 and the carrier 6305 to electrically connectthe laser 6377 and the carrier 6305. Additionally, laser photonic bump6464 may be fabricated on and/or variously added to the carrier. Laserphotonic bump 6464 may be similar to and/or comprise, and/or becomprised by TCM photonic bump and tapered waveguide photonic bump orother photonic bumps of the present disclosure.

Spacer 6418 may be placed on and/or connected to the substrate 6303and/or the laser photonic bump 6464. PhotonicPlug substrate 6426 may beattached to the spacer 6418. PhotonicPlug substrate 6426 may be similarto, and/or comprise, and/or be comprised by PhotonicPlug substratesand/or PhotonicPlug layers of the present disclosure. Optical fiber 6402(e.g., a Polarization Maintaining (PM) fiber) may be attached to thePhotonicPlug substrate 6426 (e.g., in receiving features, e.g.,V-grooves). PhotonicPlug substrate may comprise the optical elementsdescribed herein. For example, PhotonicPlug substrate 6426 may comprisefirst turning mirror 6420 and second curved mirror 6412.

Laser photonic bump 6464 may be similar to and/or comprise, and/or becomprised by TCM photonic bump and tapered waveguide photonic bump orother photonic bumps of the present disclosure. Laser photonic bump 6464may comprise TCM 6460 and TCM photonic bump curved mirror 6410 (e.g.,first curved mirror). Accordingly it may be appreciated that an opticalsignal (e.g., a laser emission) may propagate through the opticalcoupler 6400 substantially as described herein.

While some aspects of the above have been illustrated and described withrespect to single mode optical fiber, it should be appreciated thataspects of the present disclosure should not be limited to such singlemode fiber. It may be appreciated that aspects of the present disclosuremay be practiced with any type of optical fiber and/or any kind ofoptical components as optical sources and/or optical drains (e.g., PIC,chiplets, optical engines, lasers, waveguides, etc.). Accordingly, it iscontemplated that the same principles may be applied to couple PM fiber,multimode fiber and/or few mode fiber. In such applications it may beappreciated by persons of ordinary skill in the art that additionalelements may be used variously without changing the principles disclosedherein. For example, it may be appreciated that multiplexers and/orde-multiplexers may be used in such applications. However, principles asdescribed herein may similarly be applied in such applications.

Unless otherwise explicitly specified herein, the drawings may not bedrawn to scale. Additionally, identically numbered components orsimilarly numbered components (e.g., components with identical last twodigits) within different ones of the FIGS., and/or identically orsimilarly named components within different FIGS. may refer tocomponents that are substantially similar and/or different aspects ofcomponents that may achieve a similar result and/or may be similarlyconfigured.

It may be appreciated, with reference to the present disclosure, thatutilizing one or more aspects of the present disclosure, opticalconnection may be brought into buildings (e.g., homes) and connecteddirectly to devices. For example, many modern homes already receiveoptical fiber connection. Utilizing aspects of the present disclosure,the optical fiber connection may be brought into the home and directlyconnected to devices, for example, utilizing optical couplers of thepresent disclosure. Additionally, utilizing fiber-to-chip, andchip-to-chip connection of the present disclosure, optical fiberconnection may be achieved up to and into devices (e.g., personalcomputing devices, access points, servers, etc.). Thereby, bandwidth maybe increased and energy consumption may be decreased.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are described asexample implementations of the following claims.

What is claimed is:
 1. An apparatus comprising: a first optical focusingelement of an optical coupler, the first optical focusing elementconfigured to: interface an optical beam with an optical waveguide; andperform a first transformation on the optical beam; a second opticalfocusing element configured to: interface the optical beam with thefirst optical focusing element; and to perform a second transformationon the optical beam; and an optical reflecting element configured torelay the optical beam between the second optical focusing element andan optical transceiver component of a photonic integrated circuit (PIC).2. The apparatus of claim 1, wherein the optical reflecting elementcomprises a substantially flat mirror, and wherein the substantiallyflat mirror is oriented to couple the optical beam between the secondoptical focusing element and the optical transceiver component.
 3. Theapparatus of claim 1, wherein the first transformation comprises: asubstantial collimation of the optical beam by the first opticalfocusing element.
 4. The apparatus of claim 1, wherein the firsttransformation comprises: a focusing of the optical beam by the firstoptical focusing element.
 5. The apparatus of claim 1, wherein thesecond transformation comprises: a substantial collimation of theoptical beam by the second optical focusing element.
 6. The apparatus ofclaim 1, wherein the second transformation comprises: focusing of theoptical beam by the second optical focusing element.
 7. The apparatus ofclaim 1, wherein the second optical focusing element is disposed inproximity to the optical transceiver component, the second opticalfocusing element being configured to facilitate optical surfacecoupling, of the optical waveguide, to the PIC.
 8. The apparatus ofclaim 1, wherein the first optical focusing element and the secondoptical focusing element each individually comprises one or more of: acurved mirror; or a focusing lens.
 9. The apparatus of claim 1, whereinthe optical beam expands between the optical waveguide and the firstoptical focusing element, and wherein the first optical focusing elementis distanced from the optical waveguide to facilitate a predefined beamexpansion.
 10. A method comprising: disposing, in an optical coupler, afirst optical focusing element, the first optical focusing elementconfigured to: receive, from an optical waveguide, an expanding opticalbeam; and first transform the expanding optical beam; disposing, in theoptical coupler, a second optical focusing element, the second opticalfocusing element configured to: receive the first transformed opticalbeam; and second transform the received first transformed optical beam;and disposing, in the optical coupler, an optical directing componentconfigured to: relay the optical beam between the second opticalfocusing element and an optical transceiver component of a photonicintegrated circuit (PIC).
 11. The method of claim 10, wherein therelaying further comprises: directing, by a substantially flat mirror,the second transformed optical beam from the second optical focusingelement toward the optical transceiver component.
 12. The method ofclaim 10, further comprising: disposing, in the optical coupler, asecond optical directing component configured to: receive the expandingoptical beam; and direct, the expanding optical beam toward the firstoptical focusing element.
 13. The method of claim 10, wherein the firsttransforming comprises: substantially collimating the optical beam. 14.The method of claim 10, wherein the second transforming comprises:focusing the optical beam.
 15. The method of claim 10, wherein thesecond optical focusing element is further configured to: facilitateoptical surface coupling of the optical waveguide to the PIC.
 16. Themethod of claim 10, wherein the first optical focusing element isfurther configured to provide a predefined distance of a beam pathbetween the optical waveguide and the first optical focusing element tofacilitate a predefined optical beam expansion.
 17. The method of claim10, wherein the first optical focusing element and the second opticalfocusing element each individually comprise one or more of: a curvedmirror; or a focusing lens.
 18. An apparatus comprising: an opticaltransceiver component of a photonic integrated circuit (PIC); and anoptical focusing element disposed in proximity to the opticaltransceiver component, the optical focusing element configured tofacilitate optical surface coupling, of an optical waveguide, to thePIC, wherein, the optical focusing element is configured to perform atransformation of an optical beam being optically coupled between theoptical transceiver component and the optical waveguide.
 19. Theapparatus of claim 18, wherein the transformation of the optical beamcomprises a substantial collimation of the optical beam by the opticalfocusing element.
 20. The apparatus of claim 18, wherein thetransformation of the optical beam comprises focusing of the opticalbeam by the optical focusing element.
 21. The apparatus of claim 18,further comprising: a second optical focusing element, wherein thesecond optical focusing element is configured to: interface the opticalbeam with the optical focusing element; and to perform a secondtransformation of the optical beam.
 22. The apparatus of claim 21,wherein the second transformation comprises one or more of: asubstantial collimation of the optical beam; or focusing the opticalbeam.
 23. The apparatus of claim 21, further comprising a beamdeflecting element configured to relay the optical beam between theoptical transceiver component and the second optical focusing element.24. The apparatus of claim 18, further comprising: a beam deflectionelement configured to relay the optical beam between the opticaltransceiver component and the optical focusing element.
 25. Theapparatus of claim 18, wherein the optical focusing element comprisesone or more of: a curved mirror; or a focusing lens.
 26. A methodcomprising: disposing, in an optical coupler and in proximity to anoptical transceiver component of a photonic integrated circuit, anoptical focusing element, wherein the optical focusing element isconfigured to make available an optical beam for optical surfacecoupling, of an optical waveguide, to the PIC by: transforming theoptical beam; and relaying the optical beam.
 27. The method of claim 26,wherein the disposing, in the optical coupler and in proximity to theoptical transceiver component, the optical focusing element, furthercomprises: disposing, adjacent to a surface of the PIC, the opticalfocusing element.
 28. The method of claim 26, further comprising:disposing, in the optical coupler a second optical focusing element, thesecond optical focusing element configured to: interface the opticalbeam with the optical focusing element; and second transforming theoptical beam.
 29. The method of claim 26, further comprising: disposing,in the optical coupler, an optical beam deflecting element, the opticalbeam deflecting element configured to: relay the optical beam betweenthe optical transceiver component and the optical focusing element. 30.The method of claim 26, wherein the optical focusing element comprisesone or more of: a curved mirror; or a focusing lens.